Cambridge Maths Academy

P2 §1.7 Review exercise for chapter 1 본문

A-level Mathematics/Pure Mathematics 2

P2 §1.7 Review exercise for chapter 1

Cambridge Maths Academy 2022. 6. 28. 21:35
반응형

Pure mathematics Year 2

Table of contents

  1. Edexcel P2 Review exercise 1 Q1-10

1. Edexcel P2 Review exercise 1 Q1-10

Question 1. (E/P) Prove by contradiction that there are infinitely many prime numbers. [4 marks]

 

(Relevant section: P2 §1.1 Proof by contradiction.)

 

(Edexcel 2017 Specifications, P2 Review exercise 1 Q1.)

 

Solution.

 

반응형
Question 2. (E/P) Prove that the equation x22=0 has no rational solutions. You may assume that if n2 is an even integer then n is also an even integer. [4 marks]

 

(Relevant section: P2 §1.1 Proof by contradiction.)

 

(Edexcel 2017 Specifications, P2 Review exercise 1 Q2.)

 

Solution.

 

반응형
Question 3. (E) Express 4xx22x3+1x2+x as a single fraction in its simplest form. [4 marks]

 

(Relevant section: P2 §1.2 Algebraic fractions.)

 

(Edexcel 2017 Specifications, P2 Review exercise 1 Q3.)

 

Solution.

더보기
4xx22x3+1x2+x=4x(x3)(x+1)+1x(x+1)=4x2+(x3)x(x3)(x+1)=4x2+x3x(x3)(x+1)=(4x3)(x+1)x(x3)(x+1)=4x3x(x3)

 

반응형
Question 4. (P) f(x)=13x+2+3(x+2)2,x2.

(a) Show that f(x)=x2+x+1(x+2)2,x2

 

(a) Show that x2+x+1>0 for all values of x, x2.

 

(c) Show that f(x)>0 for all values of x, x2.

 

(Relevant section: P2 §1.2 Algebraic fractions.)

 

(Edexcel 2017 Specifications, P2 Review exercise 1 Q4.)

 

Solution.

더보기
(a) f(x)=13x+2+3(x+2)2=(x+2)23(x+2)+3(x+2)2=(x2+4x+4)(3x+6)+3(x+2)2=x2+x+1(x+2)2,x2.

 

(b) By completing the square, x2+x+1=(x+12)214+1=(x+12)2+3434>0.

 

(c) This gives f(x)=x2+x+1(x+2)2=(x+12)2+34(x+2)2 For x2, since both the numerator and denominator are positive, f(x)>0.

 

반응형
Question 5. (E) Show that 2x1(x1)(2x3) can be written in the form Ax1+B2x3, where A and B are constants to be found. [3 marks]

 

(Relevant section: P2 §1.3 Partial fractions.)

 

(Edexcel 2017 Specifications, P2 Review exercise 1 Q5.)

 

Solution.

더보기
Let 2x1(x1)(2x3)Ax1+B2x3A(2x3)+B(x1)(x1)(2x3) Compare the numerators on both sides: A(2x3)+B(x1)2x1 By the method of substitution: (i)x=1A=1A=1(ii)x=3212B=2B=4 and we obtain: 2x1(x1)(2x3)1x1+42x3

 

반응형
Question 6. (E) Given that 3x+7(x+1)(x+2)(x+3)Px+1+Qx+2+Rx+3, where P,Q and R are constants, find the values of P,Q and R. [4 marks]

 

(Relevant section: P2 §1.3 Partial fractions.)

 

(Edexcel 2017 Specifications, P2 Review exercise 1 Q6.)

 

Solution.

더보기
It is given that: 3x+7(x+1)(x+2)(x+3)Px+1+Qx+2+Rx+3P(x+2)(x+3)+Q(x+1)(x+3)+R(x+1)(x+2)(x+1)(x+2)(x+3) Compare the numerators on both sides: P(x+2)(x+3)+Q(x+1)(x+3)+R(x+1)(x+2)3x+7 By the method of substitution: (i)x=1(1)(2)P=4P=2(ii)x=2(1)(1)Q=1Q=1(iii)x=3(2)(1)R=2R=1 and we obtain: 3x+7(x+1)(x+2)(x+3)2x+11x+21x+3 where P=2Q=1R=1

 

반응형
Question 7. (E) f(x)=2(2x)(1+x)2,x1,x2. Find the values of A,B and C such that f(x)=A2x+B1+x+C(1+x)2 [4 marks]

 

(Relevant section: P2 §1.4 Repeated factors.)

 

(Edexcel 2017 Specifications, P2 Review exercise 1 Q7.)

 

Solution.

더보기
For partial fractions with repeated factors, let f(x)=2(2x)(1+x)2A2x+B1+x+C(1+x)2A(1+x)2+B(2x)(1+x)+C(2x)(2x)(1+x)2 Compare the numerators on both sides: A(1+x)2+B(2x)(1+x)+C(2x)2 By the method of substitution: (i)x=29A=2A=29(ii)x=13C=2C=23(iii)x=0A+2B+2C=22B=2A2C=22943=182129=49B=29 and we obtain: f(x)=2(2x)(1+x)2292x+291+x+23(1+x)229(2x)+29(1+x)+23(1+x)2 where A=29B=29C=23

 

반응형
Question 8. 14x2+13x+2(x+1)(2x+1)2Ax+1+B2x+1+C(2x+1)2. Find the values of the constants A,B and C.

 

(Relevant section: P2 §1.4 Repeated factors.)

 

(Edexcel 2017 Specifications, P2 Review exercise 1 Q8.)

 

Solution.

더보기
For partial fractions with repeated factors, let 14x2+13x+2(x+1)(2x+1)2Ax+1+B2x+1+C(2x+1)2A(2x+1)2+B(x+1)(2x+1)+C(x+1)(x+1)(2x+1)2 Compare the numerators on both sides: A(2x+1)2+B(x+1)(2x+1)+C(x+1)14x2+13x+2 By the method of substitution: (i)x=1(1)2A=14(1)2+13(1)+2=3A=3(ii)x=1212C=14(12)2+13(12)+2=72132+2=1C=2(iii)x=0A+B+C=2B=2AC=23+2=1 and we obtain: 14x2+13x+2(x+1)(2x+1)23x+1+12x+12(2x+1)2 where A=3B=1C=2

 

반응형
Question 9. (E) Given that 3x2+6x2x2+4d+ex+fx2+4, find the values of d,e and f. [4 marks]

 

(Relevant section: P2 §1.5 Algebraic division.)

 

(Edexcel 2017 Specifications, P2 Review exercise 1 Q9.)

 

Solution.

더보기

3x2+6x23(x2+4)12+6x23(x2+4)+6x143x2+6x2x2+43+6x14x2+4

Thus, d=3,e=6,f=14

 

반응형
Question 10. (E) p(x)=93x12x2(1x)(1+2x). Show that p(x) can be written in the form A+B1x+C1+2x, where A,B and C are constants to be found. [3 marks]

 

(Relevant sections: P2 §1.3 Partial fractions and §1.5 Algebraic division.)

 

(Edexcel 2017 Specifications, P2 Review exercise 1 Q10.)

 

Solution.

더보기

(i) Step 1: Algebraic division.

The denominator reads:

(1x)(1+2x)=1+x2x2 and, by algebraic division, we find: 93x12x2=6(2x2+x+1)6x6+93x=6(1+x2x2)9x+393x12x21+x2x26+9x+31+x2x293x12x2(1x)(1+2x)6+9x+3(1x)(1+2x)

 

(ii) Step 2: Partial fractions.

Let 9x+3(1x)(1+2x)B1x+C1+2xB(1+2x)+C(1x)(1x)(1+2x) Compare the numerators on both sides: B(1+2x)+C(1x)9x+3 By the method of substitution: (i)x=13B=9+3=6B=2(ii)x=1232C=92+3=152C=5 and we obtain: 9x+3(1x)(1+2x)21x+51+2x

 

Finally, we find: 93x12x2(1x)(1+2x)6+9x+3(1x)(1+2x)621x+51+2x and thus: A=6B=2C=5

 

반응형

'A-level Mathematics > Pure Mathematics 2' 카테고리의 다른 글

P2 §2. Functions and graphs  (0) 2022.06.28
P2 §1.6 Mixed exercise for chapter 1  (0) 2022.06.28
P2 §1.5 Algebraic division  (0) 2022.06.28
P2 §1.4 Repeated factors  (0) 2022.06.28
P2 §1.3 Partial fractions  (0) 2022.06.28
Comments