12mn-4m(m^2-3n+1)9（x+2)(x-2)-(3x-2)^2（x-3y+2）(x+3y+2)[(x+y)^2-(x-y)^2+4xy]/(-2x),其中x=-2 y=1/2解方程 2(2x-1)^2-8(x-1)(3+x)=34

12mn-4m(m^2-3n+1)9（x+2)(x-2)-(3x-2)^2（x-3y+2）(x+3y+2)[(x+y)^2-(x-y)^2+4xy]/(-2x),其中x=-2 y=1/2解方程 2(2x-1)^2-8(x-1)(3+x)=34
12mn-4m(m^2-3n+1)
9（x+2)(x-2)-(3x-2)^2
（x-3y+2）(x+3y+2)
[(x+y)^2-(x-y)^2+4xy]/(-2x),其中x=-2 y=1/2
解方程 2(2x-1)^2-8(x-1)(3+x)=34

12mn-4m(m^2-3n+1)9（x+2)(x-2)-(3x-2)^2（x-3y+2）(x+3y+2)[(x+y)^2-(x-y)^2+4xy]/(-2x),其中x=-2 y=1/2解方程 2(2x-1)^2-8(x-1)(3+x)=34
第一题：12mn-4m(m^2-3n+1)
=12mn-4m^3+12mn-4m
=-4m^3+24mn-4m
=-4m(m^2-6mn+1)
第二题：9（x+2)(x-2)-(3x-2)^2
=9(x^2-4)-(9x^2-12x+4)
=9x^2-36-9x^2+12x-4
=12x-40
第三题：（x-3y+2）(x+3y+2)
=(x+2-3y)(x+2+3y)
=(x+2)^2-9y^2
=x^2-9y^2+4x+4
第四题： [(x+y)^2-(x-y)^2+4xy]/(-2x), 其中x=-2 y=1/2
=[(x^2+2xy+y^2)-(x^2-2xy+y^2)+4xy]/(-2x)
=8xy/(-2x)
=-4y
=-2
第五题：2(2x-1)^2-8(x-1)(3+x)=34
(4x^2-4x+1)-4(x^2+2x-3)=17
-12x+13=17
-12x=4
x=-1/3

应该是这样解的。lz，祝你好好学习
12mn-4m(m^2-3n+1)
=4m(3n-m²+3n-1)
=4m(-m²+6n-1)
=-4m(m²-6m+1)
9（x+2)(x-2)-(3x-2)^2
=9(x²-4)-9x²+12x-4
=9x²-36-9x²+12x-4...

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应该是这样解的。lz，祝你好好学习
12mn-4m(m^2-3n+1)
=4m(3n-m²+3n-1)
=4m(-m²+6n-1)
=-4m(m²-6m+1)
9（x+2)(x-2)-(3x-2)^2
=9(x²-4)-9x²+12x-4
=9x²-36-9x²+12x-4
=12x-40
=4(3x-10)
（x-3y+2）(x+3y+2)
=(x+2-3y)(x+2+3y)
=(x+2)²-(3y)²
[(x+y)^2-(x-y)^2+4xy]/(-2x), 其中x=-2 y=1/2
原式=（x+y+x-y）(x+y-x+y)/(-2x)
=4xy/(-2x)
=-2y 代入 y=1/2
=-1
2(2x-1)^2-8(x-1)(3+x)=34
8x²-8x+2-8x²+16x-24=34
8x=34+22
8x=56
x=7

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12mn-4m(m^2-3n+1)
=4m(3n-m²+3n-1)
=4m(-m²+6n-1)
=-4m(m²-6m+1)
9（x+2)(x-2)-(3x-2)^2
=9(x²-4)-9x²+12x-4
=9x²-36-9x²+12x-4
=12x-40
=4(3x...

全部展开

12mn-4m(m^2-3n+1)
=4m(3n-m²+3n-1)
=4m(-m²+6n-1)
=-4m(m²-6m+1)
9（x+2)(x-2)-(3x-2)^2
=9(x²-4)-9x²+12x-4
=9x²-36-9x²+12x-4
=12x-40
=4(3x-10)
（x-3y+2）(x+3y+2)
=(x+2-3y)(x+2+3y)
=(x+2)²-(3y)²
[(x+y)^2-(x-y)^2+4xy]/(-2x), 其中x=-2 y=1/2
原式=（x+y+x-y）(x+y-x+y)/(-2x)
=4xy/(-2x)
=-2y 代入 y=1/2
=-1
2(2x-1)^2-8(x-1)(3+x)=34
8x²-8x+2-8x²+16x-24=34
8x=34+22
8x=56
x=7

收起

前面那位后两题有误，来个修正版的
12mn-4m(m^2-3n+1)
=4m(3n-m²+3n-1)
=4m(-m²+6n-1)
=-4m(m²-6m+1)
9（x+2)(x-2)-(3x-2)^2
=9(x²-4)-9x²+12x-4
=9x²-36-9x²+12x-4<...

全部展开

前面那位后两题有误，来个修正版的
12mn-4m(m^2-3n+1)
=4m(3n-m²+3n-1)
=4m(-m²+6n-1)
=-4m(m²-6m+1)
9（x+2)(x-2)-(3x-2)^2
=9(x²-4)-9x²+12x-4
=9x²-36-9x²+12x-4
=12x-40
=4(3x-10)
（x-3y+2）(x+3y+2)
=(x+2-3y)(x+2+3y)
=(x+2)²-(3y)²
[(x+y)^2-(x-y)^2+4xy]/(-2x), 其中x=-2 y=1/2
原式=（4xy+4xy）/(-2x)
=8xy/(-2x)
=-4y 代入 y=1/2
=-2
2(2x-1)^2-8(x-1)(3+x)=34
8x²-8x+2-8x²-16x+24=34
-24x=8
x= --1/3

收起