Hey guys,

the task: Simplify and verify.

(-x^2 + x) (7x^2 + 3x -9)

my calculation:

= -7x^4-3x^3+9x^2+7x^3+3x^2-9x

= -7x^4+4x^3+12x^2-9x

Verification: x = 1

-7x^4+4x^3+12x^2-9x

= -7(1)^4+4(1)^3+12(1)^2-9(1)

= -7+4+12-9

= 0

(-x^2 + x) (7x^2 + 3x -9)

= (-1^2+1) (7(1)^2+3(1)-9)

= (1+1) (7+3-9)

= (2) (1)

= 2

Something is wrong in my verification calculations, because both solutions should agree. Could somebody please explain my mistake?