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JAMB Mathematics Past Questions & Answers - Page 162

806.

Simplify the given expression 1cosx1+cosx

A.

1cosxsinx

B.

1 - cos x

C.

sin x

D.

1 + cos x

E.

1+cosxsinx

Correct answer is A

1cosx1+cosx = a

a2 = 1cosx1+cosx

1cosx1+cosx = 1cosx1cosx

= (1cosx)2cos2x

a2 = (1cosx)2sin2x

a = 1cosxsinx

807.

Solve the system of equation 2x + y = 32, 33y - x = 27

A.

(3, 2)

B.

(-3, 2)

C.

(3, -2)

D.

(-3, -2)

E.

(2, 2)

Correct answer is A

2x + y = 32, 33y - x = 27

2x + y = 25

33y + x = 33

x + y = 5

3yx=34y=8

y = 2

808.

If it is given that 5x + 1 + 5x = 150, then the value of x is equal to

A.

3

B.

4

C.

1

D.

2

E.

12

Correct answer is D

5x + 1 + 5x = 150

5(5x) + 5x = 150

6(5x) = 150

5x = 1506

= 25

= 52

= 2

809.

Find the solution of the equation x + 2x8 = 0

A.

(4, 16)

B.

(2, 4)

C.

(4, 1)

D.

(1, 16)

E.

(16, 16)

Correct answer is A

x + 2x8=0,Letx=y

x = y2

y2+2y - 8 = 0

(y + 4)(x - 2) = 0

y = -4 or 2

x = 16 or 4

810.

What will be the value of k so that the quadratic equation kx2 - 4x + 1 = 0 has two equal roots?

A.

2

B.

3

C.

4

D.

8

E.

14

Correct answer is C

kx2 - 4x + 1 = 0, comparing with ax2 + bx + c = 0

a = k, b = -4, c = 1 for equal root b2 = 4ac

(-4)2 = 4k

k = 164

= 4