简便计算:(x+2)(x-2)-(x-1)(x+5)

问题描述:

简便计算:(x+2)(x-2)-(x-1)(x+5)

(x+2)(x-2)-(x-1)(x+5)
=x^2-4-(x^2+5x-x-5)
=x^2-4-x^2-5x+x+5
=-4x+1

=x的平方-4-(x的平方+4x-5)
=x的平方-4-x的平方-4x+5
=-4x+1

(x+2)(x-2)-(x-1)(x+5)
=x^2-4-x^2-4x+5
=1-4x