WAEC Past Questions and Answers - Page 2256

11,276.

Find the roots of the equations: \(3m^2 - 2m - 65 = 0\)

A.

\(( -5, \frac{-13}{3})\)

B.

\(( 5, \frac{-13}{3})\)

C.

\(( 5, \frac{13}{3})\)

D.

\(( -5, \frac{13}{3})\)

Correct answer is B

Find the roots of the equations: \(3m^2 - 2m - 65 = 0\)

= \( m^2 - 15m + 13m - 65 = 0\)

= 3m(m - 5) + 13( m - 5) = 0

( m - 5)(3m + 13) = 0 

m-5 = 0 or 3m + 13 = 0

therefore, m = 5 or \(\frac{-13}{3}\)

therefore the roots of the quadratic equation = ( 5, \(\frac{-13}{3})\)

11,277.

If \(log_a 3\) = m and \(log_a 5\) = p, find \(log_a 75\)

A.

\(m^2 + p \)

B.

2m + p

C.

m + 2p

D.

\(m + p^2\)

Correct answer is C

Given: \(log_a 3\) = m and \(log_a 5\) = p
\(log_a 75\) = \(log_a (3 × 25)\)
= \(log_a (3 × 5^2)\)
= \(log_a 3 + log_a 5^2\)
= \(log_a 3 + 2log_a 5\)
Since \(log_a 3\) = m and \(log_a 5\) = p
∴ \(log_a 75\) = m + 2p

11,278.

Solve \(2^{5x} \div 2^x = \sqrt[5]{2^{10}}\)

A.

\(\frac{3}{2}\)

B.

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

C.

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

D.

\(\frac{5}{3}\)

Correct answer is B

\(2^{5x} \div 2^x = \sqrt[5]{2^{10}}\)

applying the laws of indices

\(2^{5x - x} = 2^{10(1/5)}\)

\(2^{4x} = 2^{10(1/5)}\)

\(2^{4x} = 2^2\)
Equating the powers
then 4x = 2

therefore, x = \(\frac{2}{4}\) = \(\frac{1}{2}\) 

11,279.

The interior angle of a regular polygon is 6 times its exterior angle find the number of sides of the polygon.

A.

12

B.

15

C.

10

D.

14

Correct answer is D

each interior angle of a polygon = \(\frac{(n - 2)\times 180}{n}\) where n = no of side of a polygon

each exterior angle of a polygon = \(\frac{360}{n}\)

then  \(\frac{(n - 2)\times 180}{n}\) = 6\(\times\) \(\frac{360}{n}\)

= (n - 2) 180 = 2160

= 180n - 360 = 2160

= 180n = 2160 + 360

= 180n = 2520

therefore, n = \(\frac{2520}{180}\) = 14.

11,280.

Evaluate, correct to three decimal place \(\frac{4.314 × 0.000056}{0.0067}\)

A.

0.037

B.

0.004

C.

0.361

D.

0.036

Correct answer is D

\(\frac{4.314 × 0.000056}{0.0067}\)

\(\frac{0.000242}{0.0067}\)

= 0.036 ( to 3 decimal places)