Question

plzz solve this question


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Answer 1

a^2 +b^2 +c^2 = (a+b+c)^2 -2(ab+bc+ac) .

So 7^2-2×20=49-40=9

Therefore ans is 9

Mark as brainliest

Answer 2

$\huge\mathscr\red{Heya\:Mate..!}$

Use the formula

$(a + b + c) {}^{2} = {a}^{2} + {b}^{2} + {c}^{2} + 2ab(ab + bc + ca)$