Объяснение:
3x(x+1)+(x+2)(x-3)=3x²+3x+x²-3x+2x-6=4x²+2x-6
(a+1)(a+7)-(a+2)(a+3)=a²+7a+a+7-a²-3a-2a-6=8a-5a+1=3a+1
(y-2)(y+3)-(y-1)²=y²+3y-2y-6-y²+2y-1=3y-7
(3b-5)(3b+5)-4b(3b+6)=9b²-25-12b²-24b=-3b²-24b-25
(y-4)²-(4-y)(4+y)=y²-8y+16-16+y²=2y²-8y
