初二计算 解方程 不等式组(1)4(y-z）^2-(2y+z)(-z+2y) (2)(x(x^2y^2-xy)-y(x^2+x^3y)/4x^2y (1)(x+7)(x+5)-(x-1)(x+5)=42 (2)x(2x-5)＞(x-1)(2x-1）-7 (x+1)(x+3)+8x＞(x+5)(x-5)-2
来源：学生作业帮助网 编辑：六六作业网 时间：2025/01/20 01:45:20
初二计算 解方程 不等式组(1)4(y-z）^2-(2y+z)(-z+2y) (2)(x(x^2y^2-xy)-y(x^2+x^3y)/4x^2y (1)(x+7)(x+5)-(x-1)(x+5)=42 (2)x(2x-5)＞(x-1)(2x-1）-7 (x+1)(x+3)+8x＞(x+5)(x-5)-2
初二计算 解方程 不等式组
(1)4(y-z）^2-(2y+z)(-z+2y) (2)(x(x^2y^2-xy)-y(x^2+x^3y)/4x^2y
(1)(x+7)(x+5)-(x-1)(x+5)=42 (2)x(2x-5)＞(x-1)(2x-1）-7
(x+1)(x+3)+8x＞(x+5)(x-5)-2
初二计算 解方程 不等式组(1)4(y-z）^2-(2y+z)(-z+2y) (2)(x(x^2y^2-xy)-y(x^2+x^3y)/4x^2y (1)(x+7)(x+5)-(x-1)(x+5)=42 (2)x(2x-5)＞(x-1)(2x-1）-7 (x+1)(x+3)+8x＞(x+5)(x-5)-2
1）原式=(4y^2-8yz+4z^2)-(4y^2-z^2)=-8yz+5z^2
2）原式=(x^2y(xy-1)-x^2y(1+xy))/(4x^2y)=(x^2y(xy-1-1-xy))-(4x^2y)=-2/4=-1/2
1）x^2+12x+35-x^2-4x+5=42
8x+40=42
x=2/8
x=1/4
2)2x^2-5x-2x^2+3x-1+7>0
-2x+6>0
xx^2-25-2
12x>-30
x>-2/5
所以 -2/5
(x+7)(x+5)-(x-1)(x+5)=42
解得x=四分之一