WAEC Mathematics Past Questions & Answers - Page 314

1,566.

Solve the equation: 3a + 10 = a\(^2\)

A.

a = 5 or a = 2

B.

a = -5 or a = 2

C.

a = 10 or a = 0

D.

a = 5 or a = 0

E.

a = 5 or a = -2

Correct answer is E

3a + 10 = a\(^2\)

a\(^2\) - 3a - 10 = 0

a\(^2\) - 5a + 2a - 10 = 0

a(a - 5) + 2(a - 5) = 0

(a - 5)(a + 2) = 0

a = 5 or a = -2.

1,567.

Factorize 3a\(^2\) - 11a + 6

A.

(3a - 2)(a - 3)

B.

(2a -2)(a - 3)

C.

(3a - 2)(a + 3)

D.

(3a + 2)(a - 3)

E.

(2a-3)(a + 2)

Correct answer is A

3a\(^2\) - 11a + 6

3a\(^2\) - 9a - 2a + 6

3a(a - 3) - 2(a - 3) 

= (3a - 2)(a - 3)

1,568.

For what value of y is the expression \(\frac{y + 2}{y^{2} - 3y - 10}\) undefined?

A.

y = 0

B.

y = 2

C.

y = 3

D.

y = 5

E.

y = 10

Correct answer is D

\(\frac{y + 2}{y^2 - 3y - 10}\) 

\(y^2 - 3y - 10 = 0 \implies y^2 - 5y + 2y - 10 = 0\)

\(y(y - 5) + 2(y - 5) = 0\)

\((y - 5)(y + 2) = 0\)

\(\frac{y + 2}{(y - 5)(y + 2)} = \frac{1}{y - 5}\)

\(\therefore\) At y = 5, the expression \(\frac{y + 2}{y^2 - 3y - 10}\) is undefined.

1,569.

Simplify: \((\frac{1}{4})^{-1\frac{1}{2}}\)

A.

1/8

B.

1/4

C.

2

D.

4

E.

8

Correct answer is E

\((\frac{1}{4})^{-1\frac{1}{2}}\)

= \((\frac{1}{4})^{-\frac{3}{2}}\)

= \((\sqrt{\frac{1}{4}})^{-3}\)

= \((\frac{1}{2})^{-3}\)

= \(2^3\)

= 8

1,570.

Find the number whose logarithm to base 10 is 2.6025

A.

400.4

B.

0.4004

C.

0.04004

D.

0.004004

E.

0.0004004

Correct answer is A

For the log to be 2.6025, there must be three digits before the decimal point.