Question

how to solve this question.

Answer 1

$(a + b + c) ^{2} = a {}^{2} + b {}^{2} + c {}^{2} + 2(ab + bc + ca)$
$(a + b + c) ^{2} = 250 + 6$
$a + b + c = \sqrt{256}$
$a + b + c = 16$