JAMB Mathematics Past Questions & Answers - Page 178

886.

The solution to the simultaneous equations 3x + 5y = 4, 4x + 3y = 5 is

A.

(\(\frac{-13}{11}, \frac{1}{11}\))

B.

(\(\frac{13}{11}, \frac{1}{11}\))

C.

(\(\frac{13}{11}, \frac{-1}{11}\))

D.

(\(\frac{11}{13}, \frac{1}{11}\))

E.

(13, 11)

Correct answer is B

3x + 5y = 4, 4x + 3y = 5

3x + 5y = 4 x 4

4x + 3y = 5 x 3

12x + 20y = 16.....(i)

12x + 9y = 15.......(ii)

subtract eqn.(ii) from eqn.(i)

11y = 1

y = \(\frac{1}{11}\)

12x + 20 x \(\frac{1}{11}\) = 16

12x = \(\frac{156}{11}\)

x = \(\frac{13}{11}\)

= \(\frac{13}{11}, \frac{1}{11}\)

887.

A housewife bought 3 kilograms of garri at N13.00 per kg. She deposited N160. 00 for half a cow and bought 24 oranges at 10k each. She came back home with N20.60. She therefore left home with

A.

N220.00

B.

N222.00

C.

N201.40

D.

N202.00

E.

N180.80

Correct answer is B

3 kg of garri at N13.00 per kg = N39.00
half a cow = N160.00
24 oranges at 10k each = N2.40
balance = N20.60
Adding all together = N222.00

888.

The solution to the quadratic equation 5 + 3x - 2x2 = 0 is

A.

(\(\frac{5}{2}\), 1)

B.

(5, 3)

C.

-(\(\frac{5}{2}\), -1)

D.

(\(\frac{5}{2}\), -1)

Correct answer is D

5 + 3x - 2x2 = 0, (x + 1)(5 - 2x) (expand to check)

(x + 1)(5 - 2x) = 0

when x = 1 = 0, x = -1

when 5 - 2x = 0, x = \(\frac{5}{2}\) - 1

889.

Simplify \(\frac{3}{2x - 1}\) + \(\frac{2 - x}{x - 2}\)

A.

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

B.

\(\frac{5 - x}{(2x - 1)(x - 2)}\)

C.

\(\frac{4 - 2x}{2x - 1}\)

D.

\(\frac{6 - 3x}{(2x - 1)(x - 2)}\)

Correct answer is C

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

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

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

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

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

= \(\frac{4 - 2x}{2x - 1}\)

890.

In a regular polygon of n sides, each interior angle is 144°. Find n

A.

12

B.

11

C.

10

D.

8

E.

6F

Correct answer is C

Formula for an interior angle of a polygon is (2n - 4) x 90

(2n - 4) x 90 = 144n

190n - 360 = 144n

n = \(\frac{360}{36}\)

= 10