Question

Factor this quadratic expression completely, including all complex factors-9z^2+400

Answer 1

There is a negative in front of the expression.

Answer 2

factor out the negative first to get
-( 9z^2 - 400)

Answer 3

Then you can use difference of Squares.

Answer 4

-(3z+20)(3z-20)

Answer 5

write as 400-9z*z

Answer 6

(20)^2-(3z)^2=(20+3z)(20-3z)

Answer 7

you can do it that way as well, but the point is using imaginary i Is not necessary.