WAEC Mathematics Past Questions & Answers - Page 274

1,366.

Use the graph of y = 3x\(^2\) + x - 7 above to answer the question

Find the roots of the equation y=3x\(^2\) + x - 7

A.

1.0 And -1.2

B.

1.1and-1.3

C.

1.4and-1.7

D.

2.0 and -1.9

E.

2.4 and -2.0

Correct answer is C

No explanation has been provided for this answer.

1,367.

Use the graph of y = 3x\(^2\) + x - 7 above to answer the question

What is the minimum value of y?

A.

-10

B.

-7

C.

-4

D.

-1

E.

2

Correct answer is B

No explanation has been provided for this answer.

1,368.

Solve the following simultaneous equations: x+ y = 3/2; x - y = 5/2 and use your result to find the value of 2y + x

A.

-2

B.

-1

C.

1/2

D.

1

E.

31/2

Correct answer is D

x + y = \(\frac{3}{2}\) ... (i)

x - y = \(\frac{5}{2}\) ... (ii)

(i) - (ii):

2y = \(\frac{-2}{2}\) = -1

y = \(-\frac{1}{2}\)

x + y = \(\frac{3}{2}\)

x - \(\frac{1}{2}\) = \(\frac{3}{2}\)

x = \(\frac{3}{2} + \frac{1}{2}\)

= \(\frac{4}{2}\)

x = 2

\(\therefore\) 2y + x = 2(\(-\frac{1}{2}\)) + 2

= -1 + 2 = 1.

1,369.

Solve the equation (x +2)(x - 7) = 0

A.

x = 1 or 8

B.

x = -2 or 7

C.

x = -4 or 5

D.

x = -3 or 6

E.

x= -5 or -2

Correct answer is B

(x + 2)(x - 7) = 0 x + 2 = 0 ⟹ x = -2 x - 7 = 0 ⟹ x = 7 x = -2 or 7

1,370.

Solve the equation 3x\(^2\) + 25x -18 = 0

A.

-3,2

B.

-2,3

C.

-2,9

D.

-9,2/3

E.

2/3, 9.

Correct answer is D

3x\(^2\) + 25x - 18 = 0

3x\(^2\) + 27x - 2x - 18 = 0

3x(x + 9) - 2(x + 9) = 0

(3x - 2)(x + 9) = 0

x = \(\frac{2}{3}\) or x = -9.