Question

(у-9)во второй степени -3у*(у+1)

Answer 1

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