(x-1)(x+2) (x-1)(x-5) (x-5)(x-2)
- + = | домножаем на 12
12 3 4
(x-1)(x+2)-4(x-1)(x-5)+3(x-5)(x-2)=
x^2+x-2-4(x^2-6x+5)+3(x^2-7x+10)=
x^2+ x-2-4x^2+24x-20+3x^2-21x+30=4x+8
(x-1)(x+2) (x-1)(x-5) (x-5)(x-2)
- + = | домножаем на 12
12 3 4
(x-1)(x+2)-4(x-1)(x-5)+3(x-5)(x-2)=
x^2+x-2-4(x^2-6x+5)+3(x^2-7x+10)=
x^2+ x-2-4x^2+24x-20+3x^2-21x+30=4x+8