JAMB Mathematics Past Questions & Answers - Page 78

386.

Evaluate 1 − (\(\frac{1}{5}\) x 1\(\frac{2}{3}\)) + (5 + 1\(\frac{2}{3}\))

A.

4

B.

3

C.

\(\frac{22}{3}\)

D.

3\(\frac{2}{3}\)

Correct answer is C

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

1 − (\(\frac{1}{5}\) x \(\frac{5}{3}\)) + (5 + \(\frac{5}{3}\))

1 − \(\frac{1}{3}\) + \(\frac{20}{3}\)

= \(\frac{22}{3}\)

387.

Find the range of the following set of numbers 0.4, −0.4, 0.3, 0.47, −0.53, 0.2 and −0.2

A.

1.03

B.

0.07

C.

0.03

D.

1.0

Correct answer is D

0.4, −0.4, 0.3, 0.47, −0.53, 0.2, −0.2 Range is the difference between the highest and lowest value i.e Highest − Lowest − 0.53, −0.4, −0.2, 0.2, 0.3, 0.4, 0.47 0.47 is the highest − 0.53 is the lowest ∴ = 0.47 − (− 0.53) ∴0.47 + 0.53 = 1.0

388.

If α and β are the roots of the equation 3x2 + 5x - 2 = 0, find the value of 1/α + 1/β

A.

\(\frac{-5}{3}\)

B.

\(\frac{-2}{3}\)

C.

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

D.

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

Correct answer is D

1/α + 1/β = β+α/αβ
3x2 + 5x - 2 = 0
x2 + 5x/3 - 2/3 = 0
αβ = -2/3
β+α = -5/3
Thus; β+α/αβ = -2/3 -2/3 = -5/2

389.

If \(\frac{2 \sqrt{3} - \sqrt{2}}{\sqrt{3} + 2 \sqrt{2}}\) = m + n √ 6,

find the values of m and n respectively

A.

1, − 2

B.

− 2, n = 1

C.

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

D.

\(\frac{2}{3}\)

Correct answer is B

\(\frac{2 \sqrt{3} - \sqrt{2}}{\sqrt{3} + 2 \sqrt{2}}\)= m + n√6

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


\(\frac{2 \sqrt{3} (\sqrt{3} - 2 \sqrt{2}) - \sqrt{2}(\sqrt{3} - 2 \sqrt{2})}{\sqrt{3}(\sqrt{3} - 2 \sqrt{2}) + 2 \sqrt{2}(\sqrt{3} - 2 \sqrt{2})}\)

\(\frac{2 \times 3 - 4\sqrt{6} - 6 + 2 \times 2}{3 - 2 \sqrt{6} + 2 \sqrt{6} - 4 \times 2}\)

= \(\frac{6 - 4 \sqrt{6} - \sqrt{6} + 4}{3 - 8}\)

= \(\frac{0 - 4 \sqrt{6} - 6}{5}\)

= \(\frac{10 - 5 \sqrt{6}}{5}\)

= − 2 + √6

∴ m + n\(\sqrt{6}\) = − 2 + √6

m = − 2, n = 1

390.

Simplify (3√64a3)\(^{−1}\)

A.

4a

B.

\(\frac{1}{8a}\)

C.

8a

D.

\(\frac{1}{4a}\)

Correct answer is D

(3√64a3)\(^{-1}\)

\(\frac{1}{(3√64a^3)

= \(\frac{1}{4a}\)