2017 - JAMB Mathematics Past Questions and Answers - page 4

31
In how many ways can the word MATHEMATICS be arranged?
A
\(\frac{11!}{9!2!}\)
B
\(\frac{11!}{9!2!2!}\)
C
\(\frac{11!}{2!2!2!}\)
D
\(\frac{11!}{2!2!}\)
correct option: c

MATHEMATICS is an eleven letter word = 11!

There are 2Ms and 2As and 2Es

Divide the number of repeating letters

= (\frac{11!}{2!2!2!})

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32
In how many ways can the word MACICITA be arranged?
A
\(\frac{8!}{2!}\)
B
\(\frac{8!}{3! 2!}\)
C
\(\frac{8!}{2! 2! 2!}\)
D
8!
correct option: c

MACICITA is an eight letter word = 8!

Since we have repeating letters, we have to divide to remove duplicates accordingly. There are 2A, 2C, 2I

∴ (\frac{8!}{2! 2! 2!})

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33
y is inversely proportional to x and y and 6 when x = 7. Find the constant of the variation
A
47
B
42
C
54
D
46
correct option: b

Y ∝ (\frac{1}{2})

Y = 6, X = 7

Y = (\frac{k}{x}) where k is constant

6 = (\frac{k}{7})

k = 42

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34
In the diagram MN, PQ and RS are parallel lines. What is the value of the angle marked X?
A
123o
B
170o
C
117o
D
137o
correct option: c

MN || PQ || RS

MN = PQ = RS (parallel lines)

Label the angle in the lines

a = i (corresponding angles are equal)

b = x (corresponding angles are equal)

If |MN| = |RS|

If a = i

and a = 63 = i

a + b = 180 (Adjacent interior angles are supplementary i.e add to 180)

∴ i + x = 180

63 + x = 180

x = 180 - 63

x = 1170

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35
Find the equation of the locus of a point p (x, y) such that pv = pw, where v= (1, 1) and w = (3, 5)
A
2x + 2y = 9
B
2x + 3y = 8
C
2x + y = 9
D
x + 2y = 8
correct option: d

The locus of a point p(x, y) such that pv = pw where v = (1, 1)

and w = (3, 5). This means that the point p moves so that its distance from v and w are equidistance

(\sqrt{(x − x_1)^2 + (y − y_1)^2}) = (\sqrt{(x − x_2)^2 + (y − y_2)^2})

(\sqrt{(x -1)^2 + (y - 1)^2}) = (\sqrt{(x - 3)^2 + (y - 5)^2})

square both sides

(x - 1)2 + (y - 1)2 = (x - 3)2 + (y - 5)2

x2 - 2x + 1 + y2 - 2y + 1 = x2 - 6x + 9 + y2 - 10y + 25

x2 + y2 -2x -2y + 2 = x2 + y2 - 6x - 10y + 34

Collecting like terms

x2 - x2 + y2 - y2 - 2x + 6x -2y + 10y = 34 - 2

4x + 8y = 32

Divide through by 4

x + 2y = 8

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36
Find ∫(x2 + 3x − 5)dx
A
\(\frac{x_3}{3}\) - \(\frac{3x_2}{2}\) - 5x + k
B
\(\frac{x_3}{3}\) - \(\frac{3x_2}{2}\) + 5x + k
C
\(\frac{x_3}{3}\) + \(\frac{3x_2}{2}\) - 5x + k
D
\(\frac{x_3}{3}\) + \(\frac{3x_2}{2}\) + 5x + k
correct option: c

∫xndx = (\frac{x_{n + 1}}{n + 1})

∫dx = x + k

where k is constant

∫(x2 + 3x − 5)dx

∫x2 dx + ∫3xdx − ∫5dx

(\frac{2_{2 + 1}}{2 + 1}) + (\frac{3x^{1 + 1}}{1 + 1}) − 5x + k

(\frac{x_3}{3}) + (\frac{3x_2}{2}) − 5x + k

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37
In the diagram below MN is a chord of a circle KMN centre O and radius 10cm. If
A
10cm
B
18cm
C
17cm
D
12cm
correct option: a

Find the diagram

Sin 70o

x = 10 Sin 70o

= 9.3969

Hence, length of chord MN = 2x

= 2 × 9.3969

= 18.79

= 19cm (nearest cm)

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38
If m * n = [mn − nm] for m, n belong to R, evaluate − 3 * 4
A
3
B
4
C
5
D
6
correct option: c

m * n = (\frac{m}{n}) - (\frac{m}{n})

m = − 3

n = 4

∴ − 3 × 4 = (\frac{-3}{4}) - (\frac{-4}{-3})

= (\frac{3(−3) − (− 4 × 4)}{12})

= (\frac{− 9 + 16}{12})

= (\frac{7}{12})

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39
Factorize completely x2 + 12xy + y + 3x + 3y - 18
A
(x + y + 6)(x + y -3)
B
(x - y - 6)(x - y + 3)
C
(x - y + 6)(x - y - 3)
D
(x + y - 6)(x + y + 3)
correct option: a

x + 2xy + y + 3x + 3y - 18

x + 2xy + 3x + y + 3y -18

x + 2xy - 3x + 6x + y -3y + 6y -18

x + 2xy -3x + y -3y + 6x + 6y -18

x + xy -3x + xy + y - 3y + 6x + 6y -18

x(x + y - 3) + y(x + y - 3) + 6(x + y - 3)

= (x + y - 3)(x + y + 6)

= (x + y + 6)(x + y -3)

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40
Make S the subject of the relation
p = s + \(\frac{sm^2}{nr}\)
A
s = \(\frac{nrp}{nr + m^2}\)
B
s = nr + \(\frac{m^2}{mrp}\)
C
s = \(\frac{nrp}{mr}\) + m2
D
s = \(\frac{nrp}{nr}\) + m2
correct option: d

p = s + (\frac{sm^2}{nr})

p = s + ( 1 + (\frac{m^2}{nr}))

p = s (1 + (\frac{nr + m^2}{nr}))

nr × p = s (nr + m2)

s = (\frac{nrp}{nr + m^2})

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