Question

$81a ^{2} - 72ab + 16b ^{2}$
решите пожалуйста

Answer 1

$81a ^{2} - 72ab + 16 {b}^{2} = {9}^{2} {a}^{2} - 2 \times 9a \times 4b + {4}^{2} {b}^{2} = (9a - 4b {)}^{2}$