JAMB Mathematics Past Questions & Answers - Page 200

996.

If 2x + 3y = 1 and x - 2y = 11, find (x + y)

-3

-2

Correct answer is D

2x + 3y = 1 x 2.......(i) x - 2y = 11 x 3.......(ii) 4x + 6y = 2........(iii) 3x - 6Y = 33........(4) 7x = 35 x = 5 Subt. for x 10 + 3y = 1 3y = -9 y = -3 x + y = 5 + -3 5 - 3 = 2

997.

In a racing competition, Musa covered a distance 5x km in the first hour and (x + 10)km in the next hour. He was second to Nzozi who covered a total distance of 118km in the two hours. Which of the following inequalities is correct?

-1 < x < x < 0

-3 < x < 3

0 \(\leq\) x < 18

15 < x < 18

View answer & explanation

Correct answer is C

Total distance covered by Musa in 2 hrs

= x + 10 + 5x

= 6x + 10

Ngozi = 118 km

If they are equal, 6x + 10 = 118

but 6x + 10 < 118

6x < 108

= x < 18

0 < x < 18 = 0 \(\leq\) x < 18

998.

The table below is drawn for a graph y = x³ - 3x + 1
\(\begin{array}{c|c} x & -3 & -2 & -1 & 0 & 1 & 2 & 3 \\\hline y = x^3 - 3x + 1 & 1 & -1 & 3 & 1 & -1 & 3 & 1\end{array}\)
From x = -2 to x = 1, the graph crosses the x-axis in the range(s)

-1 < x < 0 and 0 < x < 1

-2 < x < -1 and 0 < x < 1

-2 < x < -1 and -1 < x < 0

0 < x < 1

View answer & explanation

Correct answer is B

If the graph of y = x³ - 3x + 1 is plotted,the graph crosses the x-axis in the ranges -2 < x < -1 and 0 < x < 1

999.

A straight line y = mx meets the curve y = x2 - 12x + 40 in two distinct points. If one of them is (5, 5) find the other

(5, 6)

(8, 8)

(8, 5)

(7,7)

(7, 5)

View answer & explanation

Correct answer is E

When y = 5, y = x2 - 12x + 40, becomes

x2 - 12x + 40 = 5

x2 - 12x + 40 - 5 = 0

x2 + 12x + 35 = 0

x2 - 7x - 5x + 35 = 0

x(x - 7) - 5(x - 7) = 0

= (x - 5)(x - 7)

x = 5 or 7