Question

问三道初二的计算题1.（a+2b）²-a²-2ab2.-2（m-n）²+323.x（x-5

Answer 1

(a+2b）²-a²-2ab =a²+4ab+4b²-a²-2ab=4b²+2ab=2b(a+2b)

-2（m-n）²+32=-2[（m-n）²-16]=-2（m-n-4)（m-n+4)

x（x-5）²+x（x-5）（x+5）=x(x-5)(x-5)+x（x-5）（x+5）=x(x-5)[(x-5)+(x+5)]=2x²(x-5)