WAEC Mathematics Past Questions & Answers - Page 171

851.

Solve the simultaneous equation: x+y=2 and 3x-2y=1

A.

x=2 and y=1

B.

x=1 and y=1

C.

x=1 and y=2

D.

x=-1 and y=1

Correct answer is B

x + y = 2 --- eqn I
3x - 2y = 1 --- eqn II
Multiply eqn by 2
2x + 2y = 2 --- eqn III
Subtract eqn II from eqnI
5x = 5 => x = 1
Substitute 1 for x in eqn 1
1 + y = 2 => y = 1

852.

If x =3, y = 2 and z = 4 what is the value of \(3x^{2}-2y+z\)

A.

17

B.

27

C.

35

D.

71

Correct answer is B

\(3x^{2}-2y+z=3(3)^{2}-2(2)+4=27-4+4=27\)

853.

For what value of x is the expression \(\frac{2x-1}{x+3}\)not defined?

A.

3

B.

2

C.

1/2

D.

-3

Correct answer is D

x + 3 = 0 => x = -3

854.

I am x years old and my brother is 3 years older how old was my brother last year

A.

(x - 4) years

B.

(x + 2) years

C.

(3x - 1) years

D.

(3x + 1) years

Correct answer is B

If I am x years old, then my brother will be (x + 3)years old then last year my brother was (x + 3) - 1 = (x + 2)years old

855.

N140,000 is shared between ABU, Kayode and Uche. Abu has twice as much as Kayode, and Kayode has twice as much as Uche. What is Kayode's share?

A.

N80,000

B.

N40,000

C.

N20,000

D.

N10,000

Correct answer is B

\(Abu = 2x\\
Kayode = x\\
Uche = \frac{x}{2}\\
2x+x+\frac{x}{2}=140,000\\
\frac{7x}{2}=140,000\\
7x = 280,000\\
x=\frac{280,000}{7}\\
x=40,000\)Kayode receives N40,000