49(x)的平方+14x+2y-y的平方
问题描述:
49(x)的平方+14x+2y-y的平方
答
=(7x)^2+2*7x+1-(y^2-2y+1)=(7x+1)^2-(y-1)^2=(7x+y)(7x-y+2)
49(x)的平方+14x+2y-y的平方
=(7x)^2+2*7x+1-(y^2-2y+1)=(7x+1)^2-(y-1)^2=(7x+y)(7x-y+2)