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JAMB Mathematics Past Questions & Answers - Page 158

786.

The solution of the equation x² - 2x = 8 is

x = 0 or 2

x = -2 or 4

x = 2

x = -4

x = 2 or 4

View answer & explanation

Correct answer is B

x² - 2x = 8 = 8

x² - 2x - 8 = 0

(x² - 4x) + (2x - 8) = 0

When x + 2 = 0

x = -2, when x - 4 = 0

x = 4

-2 or 4

787.

x is directly proportional to y and inversely proportional to z. If x = 9 when y = 24 and z = 8, what is the value of x when y = 5 and z = 6?

$\frac{5}{6}$

3 $\frac{3}{5}$

2 $\frac{1}{2}$

1 $\frac{1}{5}$

View answer & explanation

Correct answer is D

x $\alpha$ y = x $\alpha$ $\frac{1}{z}$

x $\alpha$ $\frac{1}{z}$

x = k $\frac{y}{z}$

k = $\frac{xz}{y}$ = $\frac{9 \times 8}{24}$

= 3

x = $\frac{xz}{y}$

= $\frac{3 \times 5}{6}$

= $\frac{15}{6}$

= $\frac{5}{2}$

= 2 $\frac{1}{2}$

788.

The annul profits of a transport business were divided between the partners A and B in the ratio 3 : 5. If B received N3000 more than A, the total profit was

N5000

N1800

N12000

N24000

N8000

View answer & explanation

Correct answer is C

A : B = 3 : 5

Total ratio = 3 + 5 = 8

Let rept, the total profit, A receives $\frac{3x}{8}$

$\frac{5x}{8}$ - $\frac{3}{x}$ = 3000

$\frac{5x}{8}$ - $\frac{3x}{8}$ = 3000

= $\frac{2x}{8}$

= 3000

2x = 2400

x = 1200

N12,000

789.

In base ten, the number 101101 (base 2) equals

View answer & explanation

Correct answer is C

(101101)₂ $\begin{array}{c|c} 2^5 & 2^4 & 2^3 & 2^2 & 2^1 & 2^o\\ \hline 1 & 0 & 1 & 1 & 0 & 1\end{array}$

= 1 x 2⁵ + 0 x 2⁴ + 1 x 2³ + 1 x 2² + 0 x 2¹ + 1 x 2^o

= 32 + 0 + 8 + 4 + 0 + 1

= (45)¹⁰