Question

solve this question using property

1) (L+2m-7n)²​

Answer 1

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$\boxed{ \red{ {(a + b - c)}^{2} = {a}^{2} + {b}^{2} + {c}^{2} + 2ab - 2bc - 2ac }}$

$\implies {l}^{2} + 4 {m}^{2} + 49 {n}^{2} + 2(l)(2m) - 2(2m)( 7n) - 2(l)(7n)$

$\orange{ \therefore {l}^{2} + 4 {m}^{2} + 49 {n}^{2} + 4lm- 28mn - 14ln}$