(5y+3x-15z²)-(12y+7x+z²)
=5y+3x-15z²-12y-7x-z²
=-7y-4x-16z²(5y+3x-15z²)-(12y+7x+z²)=5y+3x-15z^-12y-7x-z^2下一步不要直接答案我还要过程然后在写答案我就是不知道最后的16z^是怎么求出来的帮帮忙(5y+3x-15z²)-(12y+7x+z²)=5y+3x-15z²-12y-7x-z²=(5y-12y)+(3x-7x)-(15z²-z²)=-7y-4x-16z²