JAMB Mathematics Past Questions & Answers - Page 418

2,086.

P is a point on one side of the straight line UV and P moves in the same direction as UV. If the straight line ST is on the locus of P and angle VUS = 60°, find angle UST.

A.

310°

B.

130°

C.

80°

D.

50°

Correct answer is B

Make a good sketch of the question, and follow this steps.
Since ST is parallel to UV => angle USR = 50°(alternate to VUS.
Angle UST = 180° - 50° = 130° (angle on a straight line)

2,088.

If α and β are the roots of the equation 3x\(^2\) + 5x - 2 = 0, find the value of 1/α + 1/β

A.

-5/3

B.

-2/3

C.

1/2

D.

5/2

Correct answer is D

1/α + 1/β = β+α/αβ
3x\(^2\) + 5x - 2 = 0
x\(^2\) + 5x/3 - 2/3 = 0
αβ = -2/3
β+α = -5/3
Thus; β+α/αβ = -5/3 ÷  -2/3 = 5/2

2,089.

Solve the inequality 2 - x > x\(^2\).

A.

x < -2 or x > 1

B.

x > 2 or x< -1

C.

-1 < x < 2

D.

-2 < x < 1

Correct answer is D

2 - x > x\(^2\)

2 - x - x\(^2\) > 0

(x+2)(x-1) < 0

Either (x + 2) > 0 and (x - 1) < 0.

x + 2 > 0 \(\implies\) x > -2.

-2 < x < 1

2,090.

A trader realizes 10x - x\(^2\) naira profit from the sale of x bags on corn. How many bags will give him the desired profit?

A.

4

B.

5

C.

6

D.

7

Correct answer is B

y = 10x - x\(^2\)
dy/dx = 10 - 2x
As dy/dx = 0,
10 - 2x = 0
2x = 10
x = 5