Question

初一数学题，求过程

Answer 1

(2)(a+b+c)(a+b-c)=(a+b)²-c²=a²+b²+2ab-c²

(3)(2a+1)²-(1-2a)²=(2a+1)²-(2a-1)²=(2a+1+2a-1)(2a+1-2a+1)=4ax2=8a
(1)(x+5)²-(x-5)²-5(2x+1)(2x-1)+x(2x)²=(x+5+x-5)(x+5-x+5)-5(4x²-1)+4x²x=20x-20x²+5+4x²x
x=1 20x-20x²+5+4x²x=20-20+5+4=9
(2)原式=(y/3)²-(x/2)²+(x/2)²-xy/6=y²/9-xy/6
x=4 y=6 y²/9-xy/6=36/9-24/6=4-4=0

希望能帮到你！

Answer 2

(a+b+c)(a+b-c)=(a+b)²-c²=a²+b²+2ab-c²

追答

(2a+1)²-(1-2a)²=(2a+1)²-(2a-1)(2a+1)=0

化简求值:
(1) =[(x+5)-(x-5)](x+5)-5(4x²-1)+x
= -20x²+11x+45
x= -1
原式=14

追问

谢谢

怎么做？

追答

=1/9y²-1/4x²+1/4x²-1/3xy
=1/9y²-1/3xy
代入x,y
= -7

追问

谢谢

追答

采纳咯