2022 - JAMB Mathematics Past Questions and Answers - page 2

11

The 10th term of an AP is 32. If the first term is 3/2, what is the 4th term?

A

35/3

B

64

C

16

D

35/2

correct option: a

Tn = a + (n-1)d

10th term = 32

32 = 3/2 + 9d 

9d = 32 - 3/2

9d = 61/2

d = 61/18

T4 = 3/2 + 3(61/18)

T4 = 3/2 + 61/6 → 35/3

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12

Tanθ is positive and Sinθ is negative. In which quadrant does θ lies

A

Third only

B

Fourth only

C

First and third only

D

Second only

correct option: a

In the third quadrant where the tangent of any angle is positive.

The sine and cosine of any angle between 180 and 270 degrees are negative.

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13

In how many ways can the letter of ZOOLOGY be arranged?

A

720

B

360

C

840

D

120

correct option: c

ZOOLOGY has 7 letters in total, with O repeated thrice hence,

\(\frac{7!}{3!}\) → \(\frac{7*6*5*4*3*2*1}{3*2*1}\)

= 840ways

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14

Find the integral of (2x+1)\(^3\)

A

\(\frac{{2x+1}^3}{8}\) + C

B

\(\frac{{2x+1}^4}{8}\) + C

C

\(\frac{{2x+1}^4}{4}\) + C

D

\(\frac{{2x+1}^2}{6}\) + C

correct option: b

Using Chain Rule,

u = 2x +1; du = 2dx → dx = \(\frac{du}{2}\)

u\(^3\) = ∫ u\(^3\) \(\frac{du}{2}\) → \(\frac{1}{2}\) ∫ u\(^3\)

=  \(\frac{1*u^4}{2*4}\) 

=  \(\frac{u^4}{8}\) →  \(\frac{{2x+1}^4}{8}\) + C

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15

If A = \(\begin{pmatrix} 2 & 1 \ 2 & 3 \ 1 & 2 \end{pmatrix}\) and B = \(\begin{pmatrix} 3 & 2 \ 4 & 2 \end{pmatrix}\). Find AB

A

\(\begin{pmatrix} 18 & 6 \ 12 & 10 \ 10 & 6 \end{pmatrix}\)

B

\(\begin{pmatrix} 10 & 6 \ 13 & 10 \ 12 & 6 \end{pmatrix}\)

C

\(\begin{pmatrix} 10 & 6 \ 12 & 10 \ 11 & 6 \end{pmatrix}\)

D

\(\begin{pmatrix} 10 & 6 \ 18 & 10 \ 11 & 6 \end{pmatrix}\)

correct option: d

Given that A = \(\begin{pmatrix} 2 & 1 \ 2 & 3 \ 1 & 2 \end{pmatrix}\) and B = \(\begin{pmatrix} 3 & 2 \ 4 & 2 \end{pmatrix}\).

We apply matrice multiplication, considering that the number of columns in A = number of rows in B

AB = \(\begin{pmatrix} (2*3)+(1*4) & (2*2)+(1*2) \ (2*3)+(3*4) & (2*2)+(3*2) \ (1*3)+(2*4) & (1*2)+(2*2) \end{pmatrix}\)

AB = \(\begin{pmatrix} (6+4) & (4+2) \ (6+12) & (4+6) \ (3+8) & (2+4) \end{pmatrix}\)

= \(\begin{pmatrix} 10 & 6 \ 18 & 10 \ 11 & 6 \end{pmatrix}\)

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16

Make v the subject of the formula from r = \( \sqrt \frac{3v}{\pi h} \)

A

v = 3 \(πr^2\) h

B

v = \(\frac{πrh}{3}\)

C

v =  \(\frac{πr^2h}{3}\)

D

v = 3πrh

correct option: c

Given r = \( \sqrt \frac{3v}{\pi h} \)

Square both sides:

r\(^2\) = \(\frac{3v}{πh}\)

cross multiply

3v = r\(^2\) * πh

v = \(\frac{πr^2h}{3}\)

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17

Find the determinant of the matrix A = \(\begin{pmatrix} 2 & 3 \ 1 & 3 \end{pmatrix}\)

A

4

B

2

C

5

D

3

correct option: d

|A| = (2*3) - (1*3)

=> 6 - 3

= 3

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18

Evaluate Log\(_2\) 8√2

A

3.0

B

4.5

C

3.5

D

2.5

correct option: c

Log\(_2\) 8√2 => Log\(_2\) √128 

=> Log\(_2\) 128\(^\frac{1}{2}\)

= \(\frac{1}{2}\) * (Log\(_2\) 128) 

=> \(\frac{1}{2}\) * (Log\(_2\) 2\(^7\))

=  7 * \(\frac{1}{2}\) * (Log\(_2\) 2)

where (Log\(_2\) 2) = 1 

=>  7 * \(\frac{1}{2}\) * 1

= \(\frac{7}{2}\) or 3.5

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19

The locus of points equidistant from a fixed point is a___

A

circle

B

perpendicular lines

C

straight line

D

bisector

correct option: a

A circle.

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20

Find the result when the numerator of \(\frac{96}{50}\) is decreased by 37.5% and its denominator decreased by 20%.

A

1.5

B

\(\frac{5}{2}\)

C

\(\frac{96}{48}\)

D

0.5

correct option: a

Numerator: 96 => 37.5% of 96 = 36

decrease by 36 => 96 - 36

new numerator = 60

Denominator: 50 => 20% of 50 = 10

decrease by 10 => 50 - 10 = 40

new denominator = 40

the new fraction = \(\frac{60}{40}\) or 1.5

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