Question

Помогите решить.
(x-3)(x-4)-2x(x-5)=

Answer 1

(х-3)(х-4)-2х(х-5)=x^2-4x-3x+12-2x^2+10x=-x^2-7x+12.

Answer 2

$(x-3)(x-4)-2x(x-5)=\\x*x+x*(-4)-3*x-3*(-4)-2x*x-2x*(-5)=\\x^2-4x-3x+12-2x^2+10x=\\(1-2)x^2+(-4-3+10)x+12=\\-x^2+3x+12$