If $(a^{2} + a b + b^{2}) = 39$ and $(a - b) = 3$ , then the value of $(a^{3} - b^{3})$ is :

111

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117

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171

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187

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Solution

The correct option is B 117
Using the identity
$(a^{3} - b^{3}) = (a^{2} + a b + b^{2}) (a - b)$ ,
$\Rightarrow$ $(a^{3} - b^{3}) = 39 \times 3 = 117$

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If (a2+ab+b2)=39 and (a−b)=3, then the value of (a3−b3) is :

The correct option is B 117Using the identity (a3−b3)=(a2+ab+b2)(a−b), ⇒ (a3−b3)=39×3=117

If $(a^{2} + a b + b^{2}) = 39$ and $(a - b) = 3$ , then the value of $(a^{3} - b^{3})$ is :

The correct option is B 117
Using the identity
$(a^{3} - b^{3}) = (a^{2} + a b + b^{2}) (a - b)$ ,
$\Rightarrow$ $(a^{3} - b^{3}) = 39 \times 3 = 117$