2000 - WAEC Mathematics Past Questions and Answers - page 4

31
Simplify \(\frac{1}{x-3}-\frac{3(x-1)}{x^2 - 9}\)
A
\(\frac{x-1}{x-3}\)
B
\(\frac{-2}{x+3}\)
C
\(\frac{x-1}{x+3}\)
D
\(\frac{4x}{x^2-9}\)
correct option: b
\(\frac{1}{x-3}-\frac{3(x-1)}{x^2 - 9}\
\frac{1}{x-3}-\frac{3(x-1)}{(x-3)(x+3)}\
\frac{x+3-3x+3}{(x-3)(x+3)};\frac{-2x+6}{(x-3)(x+3)}\
\frac{-2(x-3)}{(x-3)(x+3)}=\frac{-2}{x+3}\)
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32

Form an inequality for a distance d meters which is more than 18m, but not more than 23m

A
18 ≤ d ≤ 23
B
18 < d ≤ 23
C
18 ≤ d < 23
D
d < 18 or d > 23
correct option: b
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33

Find the equation whose roots are -8 and 5

A
\(x^2 + 13x + 40=0\)
B
\(x^2 - 13x - 40=0\)
C
\(x^2 - 3x +40=0\)
D
\(x^2 + 3x - 40=0\)
correct option: d

Equation with roots -8 and 5: (x + 8)(x - 5) = 0

\(x^2 - 5x + 8x - 40 = 0\)

\(x^2 + 3x - 40 = 0\)

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34

Make t the subject of formula \(k = m\sqrt{\frac{t-p}{r}}\)

A
\(\frac{rk^2 + p}{m^2}\)
B
\(\frac{rk^2+pm^2}{m^2}\)
C
\(\frac{rk^2-p}{m^2}\)
D
\(\frac{rk^2-p^2}{m^2}\)
correct option: b

\(k = m\sqrt{\frac{t - p}{r}}\)

\(\frac{k}{m} = \sqrt{\frac{t - p}{r}}\)

\((\frac{k}{m})^2 = \frac{t - p}{r}\)

\(rk^2 = m^2 (t - p)\)

\(\therefore m^2 t = rk^2 + m^2 p\)

\(t = \frac{rk^2 + m^2 p}{m^2}\)

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35
Solve the equation \(3y^2 = 27y\)
A
y = o or 3
B
y = 0 or 9
C
y = -3 or 3
D
y = 3 or 9
correct option: b
\(3y^2 = 27y\
3y^2 - 27y = 0\
3y(y - 9) = 0\
3y = 0 or y - 9 = 0\
y = 0 or y = 9\
y = 0 or 9\)
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36

Find the value of x such that the expression \(\frac{1}{x}+\frac{4}{3x}-\frac{5}{6x}+1\) equals zero

A
\(\frac{1}{6}\)
B
\(\frac{1}{4}\)
C
\(\frac{-3}{2}\)
D
\(\frac{-7}{6}\)
correct option: c

\(\frac{1}{x} + \frac{4}{3x} - \frac{5}{6x} + 1 = 0\)

\(\frac{6 + 8 - 5 + 6x}{6x} = 0\)

\(\frac{9 + 6x}{6x} = 0 \implies 9 + 6x = 0\)

\(6x = -9 \implies x = \frac{-3}{2}\)

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37
Given that p varies directly as q while q varies inversely as r, which of the following statements is true?
A
r varies directly as p
B
p varies inversely as r
C
p varies directly as r
D
q varies inversely as p
correct option: b
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38
In the diagram, PQS is a circle with center O. RST is a tangent at S and ∠SOP = 96o. Find ∠PST
A
42o
B
48o
C
60o
D
66o
correct option: b
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39
A bicycle wheel of radius 42cm is rolled over a distance 66 meters. How many revolutions does it make?[Take \(\pi = \frac{22}{7}\)]
A
2.5
B
5
C
25
D
50
correct option: c
circumference of the bicycle wheel
\(= 2\pi r = 2 \times \frac{22}{7} \times 42 - 264cm = 2.64m\\)
Number of revolution
\(=\frac{66}{2.64} = 25\)
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40

The height of a pyramid on square base is 15cm. if the volume is 80cm^3, find the area of the square base.

A
8cm2
B
9.6cm2
C
16cm2
D
25cm2
correct option: c

Volume of pyramid with square base = \(\frac{\text{base area} \times height}{3}\)

\(80 = \frac{\text{base area} \times 15}{3}\)

\(80 = 5 \times \text{base area}\)

\(\text{Base area} = 16 cm^2\)

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