Question

Calculeaza √a , unde a = $\sqrt{114+(2+4+6+...+286)}$

Answer 1

$a = \sqrt{144 + 2(1+2+...+143)} = \sqrt{144+ 2 \cdot \dfrac{143 \cdot (143+1)}{2}} = \sqrt{144 + 143 \cdot 144} = \sqrt{144(143+1)} = \sqrt{144 \cdot 144} = 144 \\ \\ \sqrt{a} = \sqrt{144} = 12.$