Question

Simplify
$\frac{0.7\times 0.7\times 0.7-0.2\times 0.2\times 0.2}{0.7\times 0.7+0.2\times 0.2+0.2\times 0.7}$

• A. 0.7
• B. 0.2
• C. 0.5
• D. 0.3

Answer 1

Answer: (C)

0.5

$(a^3-b^3)=(a-b)\times (a^2+ab+b^2)$

$\therefore ({0.7}^3-{0.2}^3)=(0.7-0.2)\times ({0.7}^2+0.7\times 0.2+{0.2}^2)$

$\Rightarrow ({0.7}^3-{0.2}^3)=(0.7-0.2)\times ({0.7}^2+0.7\times 0.2+{0.2}^2)$

$\Rightarrow ({0.7}^3-{0.2}^3)=\left(0.5\right)\times (0.7\times 0.7+0.2\times 0.2+0.2\times 0.7)$

$\Rightarrow ({0.7}^3-{0.2}^3)/({0.7}^2+{0.2}^2+0.2\times 0.7)=\left(0.5\right)$