七年级下册数学计算题100道及答案易错题
1、32.52-（6+9.728÷3.2）×2.5 5.x^2(y+z)^2-2xy(x-z)(y+z)+y^2(x-z)^2 =[x(y+z)-y(x-z)]^2 =(xz+yz)^2 =z^2(x+y)^2 6.3(a+2)^2+28(a+2)-20 =[3(a+2)-2][(a+2)+10] =(3a+4)(a+12) 7.(a+b)^2-(b-c)^2+a^2-c^2 =(a+b)^2-c^2+a^2-(b-c)^2 =(a+b+c)(a+b-c)+(a+b-c)(a-b+c)...