Объяснение:
3x(3x+7)-(3x+1)²=3x²+21x-(9x²+6x+1)=3x²+21x-9x²-6x-9=-6x²+15x-9
(y-4)²-(4-y)(4+y)=y²-8y+y²-(16-y²)=y²-8y+y²-16+y²=4y²-8y-16
(y-2)(y+3)-(y-1)²=y²+3y-2y-6-(y²-2y+1)=y²+y-6-y²+2y-1=3y-7
Объяснение:
3x(3x+7)-(3x+1)²=3x²+21x-(9x²+6x+1)=3x²+21x-9x²-6x-9=-6x²+15x-9
(y-4)²-(4-y)(4+y)=y²-8y+y²-(16-y²)=y²-8y+y²-16+y²=4y²-8y-16
(y-2)(y+3)-(y-1)²=y²+3y-2y-6-(y²-2y+1)=y²+y-6-y²+2y-1=3y-7