Question

平方差公式计算题40道、完全平方公式题40道（一部过程） 两部混合计算或化简求值题20道。

Answer 1

1. 8ab解法：(a+2b)^2=(a-2b)^2+na^2+4ab+4b^2=a^2-4ab+b^2+n 8ab =n 2.7解法：（a+1/a）^2=3^2 a^2+1/a^2+2=9 a^2+1/a^2 =7 3.(x^6+8)/(x^2+2)(x^2+2)n=x^6+8 n=(x^6+8)/(x^2+2) 4.x^4-6x^2y^2+4y^4(x-2y)(x-y)(x^2+3xy+2y^2) =.(x-2y)(x-y)(x+2y)(x+y) = (x-2y)(x+2y)(x-y)(x+y) =(x^2-4y^2)(x^2-y^2) =x^4-6x^2y^2+4y^4 5.x=-2(3x-2)^2-(3x+2)^2=48 9x^2-12x+4-9x^2-12x-4=48 -24x =48 x =-2 6.x=2,y=43x^2+4xy+y^2-4x+4=0 (y^2+4xy+4x^2)-x^2-4x+4=0 (y-2x)^2-(2-x)^2=0 x=2 y=47. (x+y)^2-(x+y)(x-y) =4 已知：.x^2+xy=7,……1 y^2+xy=2……2 1+2，得 x^2+y^2+2xy=9 (x+y)^2 =91-2,得 x^2+xy-y^2-xy=7-2 x^2-y^2=5&