JAMB Mathematics Past Questions & Answers - Page 162

806.

Simplify the given expression \(\sqrt{\frac{1 - cos x}{1 + cos x}}\)

A.

\(\frac{1 - cos x}{sin x}\)

B.

1 - cos x

C.

sin x

D.

1 + cos x

E.

\(\frac{1 + cos x}{sin x}\)

Correct answer is A

\(\sqrt{\frac{1 - cos x}{1 + cos x}}\) = a

a2 = \(\frac{1 - cosx}{1 + cosx}\)

\(\frac{1 - cosx}{1 + cosx}\) = \(\frac{1 - cosx}{1 - cosx}\)

= \(\frac{(1 - cosx)^2}{cos^2 x}\)

a2 = \(\frac{(1 - cos x)^2}{sin^2 x}\)

a = \(\frac{1 - cos x}{sin x}\)

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

\(\frac{3y - x = 3}{4y = 8}\)

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.

\(\frac{1}{2}\)

Correct answer is D

5x + 1 + 5x = 150

5(5x) + 5x = 150

6(5x) = 150

5x = \(\frac{150}{6}\)

= 25

= 52

= 2

809.

Find the solution of the equation x + 2\(\sqrt{x} - 8\) = 0

A.

(4, 16)

B.

(2, 4)

C.

(4, 1)

D.

(1, 16)

E.

(16, 16)

Correct answer is A

x + 2\(\sqrt{x} - 8 = 0, Let \sqrt{x} = y\)

x = \(y^2\)

\(y^2 + 2y\) - 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.

\(\frac{1}{4}\)

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 = \(\frac{16}{4}\)

= 4