JAMB Mathematics Past Questions & Answers - Page 188

936.

The solution of the quadratic equation bx2 + cx + a = 0 is given by

A.

x = b \(\pm\) \(\frac{\sqrt{b^2 - 4ac}}{2a}\)

B.

x = c \(\pm\) \(\frac{\sqrt{b^2 - 4ab}}{2b}\)

C.

x = -c \(\pm\) \(\frac{\sqrt{c^2 - 4ab}}{2b}\)

D.

x = -b \(\pm\) \(\frac{\sqrt{b^2 - 4ac}}{2b}\)

Correct answer is C

bx2 + cx + a = 0

a = b; b = c; c = a

x = -b \(\pm\) \(\frac{\sqrt{b^2 - 4ac}}{2a}\)

x = -c \(\pm\) \(\frac{\sqrt{c^2 - 4ab}}{2b}\)

937.

The factors of 6x - 5 - x2 are

A.

-(x + 3)(x + 2)

B.

(x + 5)(x + 1)

C.

(x - 5)(1 - x)

D.

(x + 1)(x + 5)

Correct answer is C

6x - 5 - x2 = (-1)(-x2 - 5 + 6x) = x2 - 6x + 5 = (x - 5)(x - 1) -(x - 1) = 1 - x = (x - 5)(1 - x)

938.

Seven years ago, the age of a father was three times that of his son, but in six years time the age of the son will be half that of his father, representing the present ages of the father and son by x and y, respectively, the two equations relating x and y are

A.

3y - x = 0; 2y - x = 0

B.

3y - x = 14; x - 2y = 6

C.

3y - x =7; x - 2y = 6

D.

3y - x = 14; y - 2x = 6

E.

x + 3y = 7; x = 2y = 12

Correct answer is B

7 years ago, Father(x - 7) years old, Son (y - 7) years x - 7 = 3(y - 7) x - 7 = 3y - 21 3y - x = -7 + 21 = 14 3y - x = 14 ... (1) In six years time, x + 6 = 2(y + 6) x + 6 = 2y + 12 2y + 12 = x + 6 12 - 6 = x - 2y 6 = x - 2y ... (2)

939.

If N560.70 is shared in the ratio 7 : 2 : 1, what is the smallest share?

A.

N392.49

B.

N56.70

C.

N113.40

D.

N112.14

E.

N56.07

Correct answer is E

7 + 2 + 1 = 10

\(\frac{1}{10}\) x 560.70

= N56.07

940.

Simplify 3 - 2 \(\div\) \(\frac{4}{5}\) + \(\frac{1}{2}\)

A.

1\(\frac{3}{4}\)

B.

-1

C.

1\(\frac{3}{10}\)

D.

1

E.

1\(\frac{9}{10}\)

Correct answer is D

3 - 2 \(\div\) (\(\frac{4}{5}\)) + \(\frac{1}{2}\)

3 - (2 x \(\frac{5}{4}\)) + \(\frac{1}{2}\) = 3 - \(\frac{10}{4}\) + \(\frac{1}{2}\)

= 3 - \(\frac{5}{2}\) + \(\frac{1}{2}\)

= \(\frac{6 - 5 + 1}{2}\)

= \(\frac{2}{2}\)

= 1