计算 (x+2y)(x-2y)+(x+1)和x(x-1)-(x-31)(x+31)
问题描述：
计算 (x+2y)(x-2y)+(x+1)和x(x-1)-(x-31)(x+31)
答
(x+2y)(x-2y)+(x+1)
=x^2-4y^2+x+1
x(x-1)-(x-31)(x+31)
=x^2-x-(x^2-961)
=x^2-x-x^2+961
=961-x