WAEC Past Questions and Answers - Page 1021

5,101.

The functions f:x → 2x\(^2\) + 3x -7 and g:x →5x\(^2\) + 7x - 6 are defined on the set of real numbers, R. Find the values of x for which 3f(x) = g(x).

A.

x = -3 or -5

B.

x = -3 or 5

C.

x = 3 or -5

D.

x = 3 or 5

Correct answer is C

f:x → 2x\(^2\) + 3x -7 and

g:x →5x\(^2\) + 7x - 6

If 3f(x) = g(x)

3(2x\(^2\) + 3x -7) = 5x\(^2\) + 7x - 6

6x\(^2\) + 9x - 21 = 5x\(^2\) + 7x - 6

6x\(^2\) - 5x\(^2\) + 9x - 7x - 21 + 6

x\(^2\) + 2x - 15 = 0

x = 3 or -5

5,102.

Consider the following statement:

x: All wrestlers are strong

y: Some wresters are not weightlifters.

Which of the following is a valid conclusion?

A.

All strong wrestlers are weightlifters

B.

Some strong wrestlers are not weightlifters

C.

Some weak wrestlers are weightlifters

D.

All weightlifters are wrestlers

Correct answer is B

No explanation has been provided for this answer.

5,103.

Simplify \(\frac{9*3^{n+1} - 3^{n+2}}{3^{n+1} - 3^{n}}\)

A.

3

B.

9

C.

27

D.

81

Correct answer is B

\(\frac{9*3^{n+1} - 3^{n+2}}{3^{n+1} - 3^{n}}\)

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

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

= \(\frac{27-9}{3-1}\)

= \(\frac{18}{2}\)

= 9

5,104.

If \(log_{10}(3x+1) + log_{10}4 = log_{10}(9x+2)\), find the value of x 

A.

\(\frac{1}{3}\)

B.

1

C.

2

D.

3

Correct answer is C

\(log_{10}(3x+1) + log_{10}4 = log_{10}(9x+2)\)

\(log_{10}4(3x+1) = log_{10}(9x+2)\)

4(3x+1) = 9x + 2

12x -4 = 9x + 2

12x - 9x = 2 + 4

3x = 6

x = 2

5,105.

(\(\frac{3√6}{√5} + \frac{√54}{3√5}\))\(^{-1}\)

A.

\(\frac{5√3}{6}\)

B.

\(\frac{3√15}{6}\)

C.

\(\frac{5√6}{12}\)

D.

\(\frac{5√3}{12}\)

Correct answer is C

(\(\frac{3√6}{√5} + \frac{√54}{3√5}\))\(^{-1}\)

= \(\frac{√5(3√5)}{3√6 + 3√6}\)

= \(\frac{3*5}{6√6} = \frac{5}{2√6}\)

= \(\frac{5*2√6}{2√6+2√6} = \frac{10√6}{4*6}\)

= \(\frac{5√6}{12}\)