Question

(у-9)во второй степени -3у*(у+1)

Answer 1

${(y - 9)}^{2} = {y}^{2} - 2 \times 9 \times y + {9}^{2} = {y}^{2} - 18y + 81$
$- 3y \times (y + 1) = - 3y \times y + ( - 3y) \times 1 = - 3 {y}^{2} - 3y$