\(W=\vec{F}.(\vec{r_{f}}-\vec{r_{i}})\)
\(=(5\widehat{i}+2\widehat{j}+7\widehat{k}).((5\widehat{i}-2\widehat{j}+\widehat{k})-(2\widehat{i}+2\widehat{j}-4\widehat{k}))\)
\(W=40J\)
So, The correct answer is 40.
Let $ P_n = \alpha^n + \beta^n $, $ n \in \mathbb{N} $. If $ P_{10} = 123,\ P_9 = 76,\ P_8 = 47 $ and $ P_1 = 1 $, then the quadratic equation having roots $ \alpha $ and $ \frac{1}{\beta} $ is:
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