Question

how do you solve (y-3)(-y+8)=9y

Answer 1

expand the brackets:

-y^2 + 8y +3y -24 - 9y = 0
-y^2 + 2y -24 = 0
y^2 - 2y + 24 = 0
y = 2 + sqrt(4 - 4*1*24) / 2
= 2 +-sqrt (-92) / 2
= 1 + sqrt23 i or 1 - sqrt23 i