F



F.6 Pure Mathematics Quiz (Binomial Theorem, Determinants, Matrix)

Time allowed: 70 minutes Total score: 40 Attempt ALL questions

1. (a) Let A = [pic]. Determine A(1.

(b) Hence, or otherwise, solve [pic].

(7 marks)

2. (a) Determine [pic]. Show that [pic].

(b) Determine [pic].

(8 marks)

3. Suppose A is a square matrix and I is the identity matrix with the same order as that of A.

Given that A3 = I, and det(A ( I) ( 0. Find det(I + A(I + A)).

(4 marks)

4. (a) Prove that [pic].

(b) Hence, or otherwise, factorize [pic].

(8 marks)

5. Given that, for n ( [pic], [pic] for a ( 1.

Evaluate [pic]. [You may express the answer in the form of nCr.]

(4 marks)

6. For n ( [pic], show that

(a) [pic]; (b) [pic].

(9 marks)

END OF PAPER

Marking Scheme of F.6 Pure Mathematics Quiz

(Binomial Theorem, Determinant, Matrix)

1.

(a) [pic] 1A for determinant + 1A

(b) [pic] [pic] 1M

[pic] 1M

[pic] 1M

[pic] i.e. x = [pic], y = ([pic] and z = 0 2A

2.

(a) [pic]= [pic] 1A

(b) [pic]

[pic] 1A for[pic]

( [pic]

(c) By (b), [pic]

[pic] 1M

[pic] 1M

[pic] 2M

= [pic] = [pic] 2A

3. A3 = I => I ( A3 = 0

(I ( A)(1 + A + A2) = 0 1M

det(I ( A)(1 + A + A2) = det0 1M

det(I ( A)det(1 + A + A2) = 0 1M

det(1 + A + A2) = 0 (∵ det(I ( A) ( 0) 1

4.

(a) [pic] 1M

= [pic] 1M

= [pic] 1M

= [pic] = [pic] 1

(b) [pic]

= [pic] (2xyzR1 + R3 ( R3) 1M

= [pic] 1A

= [pic] [by (a)] 1M

= [pic]

= [pic] 1A

5. [pic] 1M

= [pic] = [pic] 1A

By comparing coefficient of x10 of expansions in both sides, we have 1M

[pic] = [pic] 1A

6.

(a) [pic]

Differentiate w.r.t. x, [pic] 1M

[pic] 1M

Differentiate w.r.t. x, [pic] - - - (*) 1M

Put x = 0

[pic] 1M

[pic] 1

(b) By (*),[pic]

[pic]

[pic]

[pic] 1M

[pic]

[pic] 1M

By comparing coefficient of xn ( 1,

[pic] 1M

( [pic] 1

END

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