JAMB Mathematics Past Questions & Answers - Page 359

1,791.

Solve the quadratic inequalities x\(^2\) - 5x + 6 ≥ 0

A.

x ≤ 2, x ≥ 3

B.

x ≤ 3, x ≥ 2

C.

x ≤ -2, x ≥ -3

D.

x ≤-3, x ≥ 2

Correct answer is B

x\(^2\) - 5x + 6 = 0
(X-2)(X-3) = 0
X-2 = 0 implies X = 2
X-3 = 0 implies X = 3
∴ x ≤ 3, x ≥ 2

1,792.

Find the range of values of x which satisfy the inequalities 4x - 7 \(\leq\) 3x and 3x - 4 \(\leq\) 4x

A.

-4 \(\leq\) x \(\leq\) 7

B.

-7 \(\leq\) x \(\leq\) 4

C.

x \(\geq\) -7

D.

-7 \(\leq\) x \(\leq\) 6

Correct answer is A

4X - 7 \(\leq\) 3X and 3X - 4 \(\leq\) 4X
4X - 3X \(\leq\) 7 and 3X - 4X \(\leq\) 4
X \(\leq\) 7 and -X \(\leq\) 4 = X \(\geq\) -4
Range -4 \(\leq\) x \(\leq\) 7

1,793.

If p varies inversely as the square of q and p=8 when q=4, find when =32

A.

\(\pm\)16

B.

\(\pm\)8

C.

\(\pm\)4

D.

\(\pm\)2

Correct answer is D

p ∝ 1/q
p = k/q
K = q\(^2\)p
= 4\(^2\)(8)
∴p = 128/q
32 = 128/q
q\(^2\) = 128/32
q\(^2\) = 4
q = √4 = \(\pm\) 2

1,794.

If x - 3 is directly proportional to the square of y and x = 5 when y =2, find x when y = 6.

A.

30

B.

21

C.

16

D.

12

Correct answer is B

(x – 3) ∝ y2
X-3 = Ky2
K = X-3 / y2
= 5-2/22
= 2/4
= 1/2
∴X-3 = 1/2y2
X-3 = 1/2 (6)2
X-3 = 1/2 x 36/1
X-3 = 18
X = 21

1,795.

Factorize completely; (4x+3y)\(^2\) - (3x-2y)\(^2\) 

A.

(x+5y)(7x+y)

B.

(x+5y)(7x-y)

C.

(x-5y)(7x+y)

D.

(x-5y)(7x-y)

Correct answer is A

(4x+3y)\(^2\) - (3x-2y)\(^2\) 

Using the differences of two squares:

(4x+3y+3x-2y)(4x+3y-(3x-2y))

(4x+3y+3x-2y)(4x+3y-3x+2y)

(x+5y)(7x+y)