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JAMB Mathematics Past Questions & Answers - Page 157

781.

Simplify 5x×25x1125x+1

A.

52x + 1

B.

5x + 1

C.

5-5

D.

52

E.

53

Correct answer is C

5x×25x1125x+1 = 5x×52x253x+3

= 5x+2x253x+3

= 53x253x+3

= 53x23x3

= 55

782.

Rationalize the denominator of the expression 6+25436

A.

12+45+75+6339

B.

(24+186+85+630)38

C.

24+36+85+63019

D.

15+35+185+63036

E.

(12+45+96+330)19

Correct answer is B

Rationalize using the reciprocal of the denominator to multiply through 

(i.e. Multiply both numerator and denominator using 4+36 )

Watch your signs in the course of this.

783.

A square of cardboard is taped at the perimeter by a piece of ribbon 20cm long. What is the area of the board?

A.

20sq.cm

B.

100sq.cm

C.

25sq.cm

D.

16sq.cm

E.

36sq.cm

Correct answer is C

Area of a square = 4(5) where S is each sides of the square

Perimeter = 20(given)

4S = 20

S = 204

= 5

Area s2 = 52

= 25

784.

Multiply (3x + 5y + 4z) by (2x - 3y + z)

A.

6x2 + xy - 15y2 + 4z2 + 11xz - 7yz

B.

6x2 + 3xy - 15y2 + 4z2

C.

6x2 + 3xy - y2 + 4z2

D.

6x2 + 3xy - 15y + z2

Correct answer is A

(3x + 5y + 4z)(2x - 3y + z)

6x2 + 9xy + 3x2 + 10xy - 15y2 + 5yz + 8xz - 12yz + 4z2

= 6x2 + xy - 15y2 + 4z2 + 11xz - 7yz

785.

A trader goes to Ghana for y days with y cedis. For the first x days, he spends X cedis per day. The amount he has to spend per day for the rest of his stay is

A.

y(yx)yx cedis

B.

YyXx)yx cedis

C.

YXy)yx cedis

D.

YXyx cedis

E.

YXxyx cedis

Correct answer is E

The amount he has to spend per day for the rest of his stay is YXxyx cedis