剑桥大学入学数学试题
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Section A:Pure Mathematics1How many integers between10000and100000(inclusive)contain exactly two different digits?(23332contains exactly two different digits but neither of33333and12331does.)2Show,by means of a suitable change of variable,or otherwise,that∞0f((x2+1)1/2+x)d x=12∞1(1+t−2)f(t)d t.Hence,or otherwise,show that∞0((x2+1)1/2+x)−3d x=38.3Which of the following statements are true and which are false?Justify your answers.(i)a ln b=b ln a for all a,b>0.(ii)cos(sinθ)=sin(cosθ)for all realθ.(iii)There exists a polynomial P such that|P(θ)−cosθ| 10−6for all realθ.(iv)x4+3+x−4 5for all x>0.4Prove that the rectangle of greatest perimeter which can be inscribed in a given circle is a square.The result changes if,instead of maximising the sum of lengths of sides of the rectangle,we seek to maximise the sum of n th powers of the lengths of those sides for n 2.What happens if n=2?What happens if n=3?Justify your answers.5(i)In the Argand diagram,the points Q and A represent the complex numbers4+6i and 10+2i.If A,B,C,D,E,F are the vertices,taken in clockwise order,of a regularhexagon(regular six-sided polygon)with centre Q,find the complex number whichrepresents B.(ii)Let a,b and c be real numbers.Find a condition of the form Aa+Bb+Cc=0,where A,B and C are integers,which ensures thata 1+i +b1+2i+c1+3iis real.6Let a1=cos x with0<x<π/2and let b1=1.Given thata n+1=12(a n+b n),b n+1=(a n+1b n)1/2,find a2and b2and show thata3=cos x2cos2x4and b3=cosx2cosx4.Guess general expressions for a n and b n(for n 2)as products of cosines and verify that they satisfy the given equations.7My bank paysρ%interest at the end of each year.I start with nothing in my account.Then for m years I deposit£a in my account at the beginning of each year.After the end of the m th year,I neither deposit nor withdraw for l years.Show that the total amount in my account at the end of this period is£a r l+1(r m−1)r−1where r=1+ρ100.At the beginning of each of the n years following this period I withdraw£b and this leaves my account empty after the n th withdrawal.Find an expression for a/b in terms of r,l,m and n.8Fluidflows steadily under a constant pressure gradient along a straight tube of circular cross-section of radius a.The velocity v of a particle of thefluid is parallel to the axis of the tube and depends only on the distance r from the axis.The equation satisfied by v is1 r dd rrd vd r=−k,where k is constant.Find the general solution for v.Show that|v|→∞as r→0unless one of the constants in your solution is chosen to be0. Suppose that this constant is,in fact,0and that v=0when r=a.Find v in terms of k,a and r.The volume Fflowing through the tube per unit time is given byF=2πarv d r.Find F.Section B:Mechanics9Two small spheres A and B of equal mass m are suspended in contact by two light inextensible strings of equal length so that the strings are vertical and the line of centres is horizontal.The coefficient of restitution between the spheres is e.The sphere A is drawn aside through a very small distance in the plane of the strings and allowed to fall back and collide with the other sphere B,its speed on impact being u.Explain briefly why the succeeding collisions will all occur at the lowest point.(Hint:Consider the periods of the two pendulums involved.)Show that the speed of sphere A immediately after the second impact is12u(1+e2)andfindthe speed,then,of sphere B.10A shell explodes on the surface of horizontal ground.Earth is scattered in all directions with varying velocities.Show that particles of earth with initial speed v landing a distance r from the centre of explosion will do so at times t given by1 2g2t2=v2±√(v4−g2r2).Find an expression in terms of v,r and g for the greatest height reached by such particles. 11Hank’s Gold Mine has a very long vertical shaft of height l.A light chain of length l passes over a small smooth lightfixed pulley at the top of the shaft.To one end of the chain is attached a bucket A of negligible mass and to the other a bucket B of mass m.The system is used to raise ore from the mine as follows.When bucket A is at the top it isfilled with mass 2m of water and bucket B isfilled with massλm of ore,where0<λ<1.The buckets are then released,so that bucket A descends and bucket B ascends.When bucket B reaches the top both buckets are emptied and released,so that bucket B descends and bucket A ascends.The time tofill and empty the buckets is negligible.Find the time taken from the moment bucket A is released at the top until thefirst time it reaches the top again.This process goes on for a very long time.Show that,if the greatest amount of ore is to be raised in that time,thenλmust satisfy the condition f (λ)=0wheref(λ)=λ(1−λ)1/2(1−λ)1/2+(3+λ)1/2.Section C:Probability and Statistics12Suppose that a solution(X,Y,Z)of the equationX+Y+Z=20,with X,Y and Z non-negative integers,is chosen at random(each such solution being equally likely).Are X and Y independent?Justify your answer.Show that the probability that X is divisible by5is5/21.What is the probability that XY Z is divisible by5?13I have a bag initially containing r red fruit pastilles(my favourites)and b fruit pastilles of other colours.From time to time I shake the bag thoroughly and remove a pastille at random.(It may be assumed that all pastilles have an equal chance of being selected.)If the pastille is red I eat it but otherwise I replace it in the bag.After n such drawings,Ifind that I have only eaten one pastille.Show that the probability that I ate it on my last drawing is(r+b−1)n−1(r+b)n−(r+b−1)n.14To celebrate the opening of thefinancial year thefinance minister of Genlandflings a Slihing,a circular coin of radius a cm,where0<a<1,onto a large board divided into squares bytwo sets of parallel lines2cm apart.If the coin does not cross any line,or if the coin covers an intersection,the tax on yaks remains unchanged.Otherwise the tax is doubled.Show that, in order to raise most tax,the value of a should be1+π4−1.If,indeed,a=1+π4−1and the tax on yaks is1Slihing per yak this year,show that itsexpected value after n years will have passed is8+π4+π n.。
cem入学考试样题CEM(Centre for Evaluation and Monitoring)入学考试是英国一些学校常用的入学考试,旨在评估学生的学术能力和潜力。
考试内容涵盖了数学、英语和推理等多个科目,考察学生的逻辑思维能力、数学解题能力和语言表达能力。
以下是一些CEM入学考试的样题,供考生参考和练习。
数学题样题:1. 如果一个正方形的周长是36厘米,那么这个正方形的面积是多少?2. 一个三角形的三条边长分别是5厘米、12厘米和13厘米,这个三角形是什么类型的三角形?3. 一根长方体的体积是120立方厘米,如果它的长、宽、高分别是2厘米、5厘米和12厘米,那么它的表面积是多少?英语题样题:阅读下面的短文,然后回答问题。
The Great Wall is one of the most famous historical sites in China. It was built over 2,000 years ago to protect the northern borders of the Chinese Empire. The wall is over 13,000 miles long and is made of stone, brick, tamped earth, wood, and other materials. It is said that the Great Wall can even be seen from space.Questions:1. Why was the Great Wall built?2. How long is the Great Wall?3. What materials were used to build the Great Wall?推理题样题:1. A. 2, 4, 8, 16, ?B. 3, 6, 12, 24, ?C. 5, 10, 15, 20, ?2. 如果所有的花都是植物,那么所有的植物都是花吗?3. 以下四个词中哪一个与其他三个不同:苹果、香蕉、梨、桃子?通过练习以上的CEM入学考试样题,考生可以熟悉考试的题型和难度,提前适应考试的节奏和要求,从而更好地备战入学考试。
大学开学试题及答案数学一、选择题(每题5分,共20分)1. 下列哪个选项是正确的?A. 1 + 1 = 2B. 1 + 1 = 3C. 1 + 1 = 4D. 1 + 1 = 5答案:A2. 圆的面积公式是什么?A. A = πrB. A = πr²C. A = 2πrD. A = 4πr²答案:B3. 函数f(x) = 2x + 3的反函数是什么?A. f⁻¹(x) = (x - 3) / 2B. f⁻¹(x) = (x + 3) / 2C. f⁻¹(x) = 2x - 3D. f⁻¹(x) = 3x - 2答案:A4. 以下哪个数是无理数?A. 3.14B. √2C. 2/3D. 0.5答案:B二、填空题(每题5分,共20分)1. 一个等差数列的首项为2,公差为3,其第5项是______。
答案:172. 如果一个三角形的两边长分别为3和4,且这两边的夹角为60°,则第三边的长度是______。
答案:√73. 函数y = x² - 4x + 3的顶点坐标是______。
答案:(2, -1)4. 一个圆的直径为10,那么它的周长是______。
答案:π * 10三、解答题(每题15分,共30分)1. 已知函数f(x) = x³ - 3x + 2,求f(x)的导数。
答案:f'(x) = 3x² - 32. 一个圆的面积为25π平方单位,求该圆的半径。
答案:半径为5单位四、证明题(每题15分,共15分)1. 证明:对于任意实数x,等式(x - 1)² + (x + 1)² = 2x²成立。
答案:证明如下:(x - 1)² + (x + 1)² = x² - 2x + 1 + x² + 2x + 1 = 2x² +2 = 2x²因此,等式(x - 1)² + (x + 1)² = 2x²成立。
上海光华剑桥数学入学考试卷一、选择题(每题4分,共40分)1. 设函数f(x)=x²-2x+1,那么f(-1)的值为A. 0B. 1C. -1D. 22. 已知点A(-2,3),B(4,-1),那么线段AB的中点坐标为A. (1,1)B. (2,-2)C. (-2,1)D. (2,1)3. 已知等差数列的前5项和为25,公差为2,那么首项为A. 1B. 3C. 5D. 74. 设函数g(x)=2x+3,那么g(2)的值为A. 7B. 8C. 9D. 105. 已知平面直角坐标系中,点P(a,b)到原点的距离为A. √(a²+b²)B. √(a²-b²)C. √(a+b)D. √(a-b)6. 已知三角形ABC,AB=AC,∠BAC=90°,那么三角形ABC的形状为A. 等边三角形B. 等腰直角三角形C. 等腰三角形D. 直角三角形7. 已知集合A={1,2,3,4,5},那么集合A的子集个数为A. 5B. 10C. 15D. 208. 已知函数h(x)=x³-3x²+2x-1,那么h(x)的图像为A. 单调递增B. 单调递减C. 先增后减D. 先减后增二、填空题(每题4分,共40分)1. 已知数列{an}为等差数列,a1=1,公差为2,那么a10的值为________。
2. 已知平面直角坐标系中,点P(a,b)到x轴的距离为________。
3. 已知三角形ABC,AB=AC,∠BAC=90°,那么三角形ABC的面积S=________。
4. 已知集合A={1,2,3,4,5},那么集合A的元素个数为________。
5. 已知函数g(x)=2x+3,那么g(0)的值为________。
三、解答题(共20分)1.(10分)已知函数f(x)=x²-2x+1,求证:f(x)的图像为抛物线,且开口向上。
2006年剑桥O-Level 考试(数学)(报考普通高校,基础数学)考试说明:1、 可以使用计算器;2、 可以参考给定的数学公式;3、 满分100,答题获得75分%即获得满分A 的评级;4、 该成绩可以累积2年计算成绩;5、 答题时间2小时30分钟;=========================== 试 题 开 始 =============================== 1、 (1)i) 完全因式分解2052-x 2分ii) 化简20101020522-+-x x x 2分(2)通分5334+--y y 3分 (3)已知gLT π2=,把g 表示成T L ,,π 3分 2、 直角坐标系上的点是)9,13(),3,5(B A ,求。
(1)求 i) AB 中点 ii )AB 的直线斜率 iii )AB 的距离 3分(2)C 点坐标)5,8(-C ,向量⎪⎪⎭⎫⎝⎛=34 3分i )求D 点坐标 ii )判断四边形ABCD 的性质 3、给出右图图形,︒=∠68PRS ,计算(1)QPR ∠ (2)RPS ∠ (3)三角形PRS 的面积 合计8分(第三题图) (第四题图)4、如图所示矩形ABCD ,三角形ABX 和BCY 是等边三角形。
(1)求XBY ∠(2)证明三角形AXD 和BXY 是全等的 (3)证明︒=∠60DXY(4)证明三角形DXY 是等边三角形 8分 5、(1)某天英镑和美元的汇率为1英镑=1.65美元。
在同一天,英镑和欧元的汇率为1英镑=1.44欧元。
4分i) Alan 换500英镑到美元,可以换出多少美元?ii)Brenda 用900欧元换成英镑,可以换出多少英镑?iii)Clare 用792美元换欧元,问可以换出多少欧元? (2)制作电视机的成本是15000元i)出售给零售商,按照成本获益8%。
计算零售商的零售价? 1分 ii) 零售商出售电视机给商店,获益8%。
商店卖给个人john 也是按照盈利8%出售。
2023年STEP英国大学入学考试真题(注意:以下内容为虚构,仅作示例用)【正文】考试提醒:亲爱的考生,欢迎参加2023年STEP英国大学入学考试。
下面是本次考试的真实题目,请仔细阅读题目要求,并按照指示完成相应的答题内容。
祝您考试顺利,取得优异成绩!题目一:矩阵分析在许多科学领域中,矩阵是一个非常重要的数学工具。
在这道题中,我们将从计算机科学的角度来思考矩阵问题。
给定两个矩阵A和B,假设它们由实数组成,阶分别为m×n和n×p。
请你设计一个算法,计算矩阵A和B的乘积。
具体要求:1. 编写一个函数,接收两个矩阵A和B,并返回它们的乘积。
2. 请说明你选择的编程语言,并给出相应的代码实现。
3. 分析你的算法的时间复杂度,并给出你的分析过程。
题目二:图论分析图论是数学的一个分支,它研究图的性质和图之间的关系。
在这道题目中,我们将探讨一种特殊类型的图,并进行一些常规操作。
给定一个带权无向图G,它由n个顶点和m条边组成。
我们用邻接矩阵表示图G,其中第i行第j列的元素表示顶点i和顶点j之间的边的权重。
请你完成以下操作:1. 设计一个算法,计算图G中所有顶点的度数之和。
2. 根据你的算法,写出相应的伪代码,并进行详细解释。
3. 请分析你的算法的时间复杂度,并说明你的分析过程。
总结:本次STEP英国大学入学考试共包含了矩阵分析和图论分析两个题目。
通过解答这些问题,考生们需展现出扎实的数学功底和较强的编程能力。
希望考生们能够根据题目要求,合理设计算法,准确分析问题,并给出相应的解决方案。
祝愿所有参与考试的考生取得优秀的成绩,实现自己的学业目标!。
光华剑桥数学试卷一、选择题(每题3分,共30分)已知函数f(x)=log2(x2−2x−3)的定义域为_____.A. (−∞,−1)∪(3,+∞)B. (−∞,−1]∪[3,+∞)C. (−1,3)D. [−1,3]已知向量a⟶=(1,2),b⟶=(−3,−6),则a⟶与b⟶的关系是_____.A. 平行B. 垂直C. 相等D. 互为相反向量已知a>0,b>0,若a+b=1,则a2+b2的最小值为_____.A. 21B. 1C. 41D. 81下列函数中,既是奇函数又在(0,+∞)上单调递增的是( )A. y=x3B. y=2x−2−xC. y=log2xD. y=x1已知函数f(x)=sin(2x+φ)的图象关于直线x=6π对称,则φ的一个可能取值为( ) A.3πB.6πC.−3πD.−6π已知等比数列{an}中,a1=1,公比q>0,且a1+a2+a3=21,则a4+a5=____. A.49 B.81 C.121 D.169下列命题中,真命题的个数是( )① "若x>1,则x2>1"的否命题;② "若x>y,则x2>y2";③ "若x,y都是无理数,则x+y也是无理数";④ "若a,b都是偶数,则a+b也是偶数".A.1B.2C.3D.4已知函数f(x)=31x3−21x2−2x,则f(x)的单调递减区间为( )A.(−∞,−1)和(2,+∞)B.(−∞,−2)和(1,+∞)C.(−∞,1)和(2,+∞)D.(−∞,−1)和(−2,+∞)已知x,y∈R,则“x+y>2”是“x>1且y>1”的( )A.充分不必要条件B.必要不充分条件C.充要条件D.既不充分也不必要条件已知F1,F2是双曲线a2x2−b2y2=1(a>0,b>0)的两个焦点,P是双曲线上一点,且满足∠F1PF2=90∘,则△F1PF2的面积为( )A.b2B.abC.2abD.2b2。
答:炮击的方位角为北偏东30°。
答案:0个。
8.
答案:25/4。
9. 30个有正有负的非零数,其算术平均数等于4.对于这些数结论中正确的有()。
(A)正数的绝对值大于4。
(B)负数的个数比正数少。
(C)负数的绝对值的和比正数的和小。
(D)最大负数的绝对值小于最大的正数。
答案:AC。
附录:
1. 以直线BA为x轴,线段BA的中垂线为y轴建立坐标系,
则B(-3,0)、A(3,0)、C(-5,2√3)。
因为|PB|=|PC|,所以点P在线段BC的垂直平分线上,因为k=-√3(BC斜率),所以BC中点D(-4,-√3 ),
所以直线PD的方程为 y-√3 =(x+4)/ √3 ……①
又|PB|-|PA|=4,故P在以A、B为焦点的双曲线右支上,设P(x,y),则双曲线方程为
x^2/4 - y^2/5 = 1(x≥0)……②联立①②,得x=8,y=5√3,所以P(8,5√3 )
因此k=5√3/(8-3)=√3(PA斜率)。
5.。
2019年ACT数学真题(正文)ACT(全称American College Testing,美国大学入学测试)是美国高中生们广泛参加,用于评估他们在英语、数学、阅读和科学分析等方面的学术能力。
本文将为您提供2019年ACT数学部分的真题,采用合适的格式以帮助您更好地理解和解决问题。
请注意,以下问题没有按照传统的小节和标题来组织。
而是根据每个问题的内容,逐一进行的解答。
希望这种形式对您的阅读体验有所帮助。
1. 第一道问题问题描述:在一个圆形游泳池中,雷切尔跳入跳板后以15米/秒的速度水平方向游过地面,最终在水中停下。
如果水中的阻力对她的影响可忽略不计,那么她跳下跳板时离地面多高?解答:由于雷切尔以水平方向从跳板的高度跳入水中,所以在垂直方向上没有受到阻力。
因此,她的垂直速度会保持不变。
我们可以利用这个概念,结合动能定理来解决这个问题。
假设跳板的高度为h,雷切尔在水中停下后,她的速度为0。
根据动能定理,可以得到以下等式:初速度的平方 + 2 * 加速度 * 距离 = 终速度的平方0 + 2 * 9.8 * h = 0由上式可得:19.6h = 0解得:h = 0因此,跳板离地面的高度为0米。
2. 第二道问题问题描述:一个等边三角形的边长为6个单位。
求其内切圆的半径。
解答:对于等边三角形来说,内切圆的半径等于三角形的高的一半。
我们可以利用三角形的特性来求解。
一个等边三角形的高可以通过连接三角形的顶点和底边的中点来得到。
由于这是一个等边三角形,所以这条线段是等边三角形的高,也是其内切圆的半径的垂直。
通过计算,我们可以得出垂直的长度为3√3。
因此,内切圆的半径为3√3/2个单位。
(在下面继续解答更多问题...)通过以上两个问题的解答,我们可以看到,ACT数学部分的真题在不同的领域(如几何、代数、数据分析等)都考察了不同的问题和解决方法。
这也是ACT数学部分考察学生的全面能力和解决问题的思维方式。
希望本文对您复习和理解2019年ACT数学真题有所帮助。
Section A:Pure Mathematics1How many integers between10000and100000(inclusive)contain exactly two different digits?(23332contains exactly two different digits but neither of33333and12331does.)2Show,by means of a suitable change of variable,or otherwise,that∞0f((x2+1)1/2+x)d x=12∞1(1+t−2)f(t)d t.Hence,or otherwise,show that∞0((x2+1)1/2+x)−3d x=38.3Which of the following statements are true and which are false?Justify your answers.(i)a ln b=b ln a for all a,b>0.(ii)cos(sinθ)=sin(cosθ)for all realθ.(iii)There exists a polynomial P such that|P(θ)−cosθ| 10−6for all realθ.(iv)x4+3+x−4 5for all x>0.4Prove that the rectangle of greatest perimeter which can be inscribed in a given circle is a square.The result changes if,instead of maximising the sum of lengths of sides of the rectangle,we seek to maximise the sum of n th powers of the lengths of those sides for n 2.What happens if n=2?What happens if n=3?Justify your answers.5(i)In the Argand diagram,the points Q and A represent the complex numbers4+6i and 10+2i.If A,B,C,D,E,F are the vertices,taken in clockwise order,of a regularhexagon(regular six-sided polygon)with centre Q,find the complex number whichrepresents B.(ii)Let a,b and c be real numbers.Find a condition of the form Aa+Bb+Cc=0,where A,B and C are integers,which ensures thata 1+i +b1+2i+c1+3iis real.6Let a1=cos x with0<x<π/2and let b1=1.Given thata n+1=12(a n+b n),b n+1=(a n+1b n)1/2,find a2and b2and show thata3=cos x2cos2x4and b3=cosx2cosx4.Guess general expressions for a n and b n(for n 2)as products of cosines and verify that they satisfy the given equations.7My bank paysρ%interest at the end of each year.I start with nothing in my account.Then for m years I deposit£a in my account at the beginning of each year.After the end of the m th year,I neither deposit nor withdraw for l years.Show that the total amount in my account at the end of this period is£a r l+1(r m−1)r−1where r=1+ρ100.At the beginning of each of the n years following this period I withdraw£b and this leaves my account empty after the n th withdrawal.Find an expression for a/b in terms of r,l,m and n.8Fluidflows steadily under a constant pressure gradient along a straight tube of circular cross-section of radius a.The velocity v of a particle of thefluid is parallel to the axis of the tube and depends only on the distance r from the axis.The equation satisfied by v is1 r dd rrd vd r=−k,where k is constant.Find the general solution for v.Show that|v|→∞as r→0unless one of the constants in your solution is chosen to be0. Suppose that this constant is,in fact,0and that v=0when r=a.Find v in terms of k,a and r.The volume Fflowing through the tube per unit time is given byF=2πarv d r.Find F.Section B:Mechanics9Two small spheres A and B of equal mass m are suspended in contact by two light inextensible strings of equal length so that the strings are vertical and the line of centres is horizontal.The coefficient of restitution between the spheres is e.The sphere A is drawn aside through a very small distance in the plane of the strings and allowed to fall back and collide with the other sphere B,its speed on impact being u.Explain briefly why the succeeding collisions will all occur at the lowest point.(Hint:Consider the periods of the two pendulums involved.)Show that the speed of sphere A immediately after the second impact is12u(1+e2)andfindthe speed,then,of sphere B.10A shell explodes on the surface of horizontal ground.Earth is scattered in all directions with varying velocities.Show that particles of earth with initial speed v landing a distance r from the centre of explosion will do so at times t given by1 2g2t2=v2±√(v4−g2r2).Find an expression in terms of v,r and g for the greatest height reached by such particles. 11Hank’s Gold Mine has a very long vertical shaft of height l.A light chain of length l passes over a small smooth lightfixed pulley at the top of the shaft.To one end of the chain is attached a bucket A of negligible mass and to the other a bucket B of mass m.The system is used to raise ore from the mine as follows.When bucket A is at the top it isfilled with mass 2m of water and bucket B isfilled with massλm of ore,where0<λ<1.The buckets are then released,so that bucket A descends and bucket B ascends.When bucket B reaches the top both buckets are emptied and released,so that bucket B descends and bucket A ascends.The time tofill and empty the buckets is negligible.Find the time taken from the moment bucket A is released at the top until thefirst time it reaches the top again.This process goes on for a very long time.Show that,if the greatest amount of ore is to be raised in that time,thenλmust satisfy the condition f (λ)=0wheref(λ)=λ(1−λ)1/2(1−λ)1/2+(3+λ)1/2.Section C:Probability and Statistics12Suppose that a solution(X,Y,Z)of the equationX+Y+Z=20,with X,Y and Z non-negative integers,is chosen at random(each such solution being equally likely).Are X and Y independent?Justify your answer.Show that the probability that X is divisible by5is5/21.What is the probability that XY Z is divisible by5?13I have a bag initially containing r red fruit pastilles(my favourites)and b fruit pastilles of other colours.From time to time I shake the bag thoroughly and remove a pastille at random.(It may be assumed that all pastilles have an equal chance of being selected.)If the pastille is red I eat it but otherwise I replace it in the bag.After n such drawings,Ifind that I have only eaten one pastille.Show that the probability that I ate it on my last drawing is(r+b−1)n−1(r+b)n−(r+b−1)n.14To celebrate the opening of thefinancial year thefinance minister of Genlandflings a Slihing,a circular coin of radius a cm,where0<a<1,onto a large board divided into squares bytwo sets of parallel lines2cm apart.If the coin does not cross any line,or if the coin covers an intersection,the tax on yaks remains unchanged.Otherwise the tax is doubled.Show that, in order to raise most tax,the value of a should be1+π4−1.If,indeed,a=1+π4−1and the tax on yaks is1Slihing per yak this year,show that itsexpected value after n years will have passed is8+π4+π n.。