1.1-x+4分之x^22.(x-y)^2-4(x-y-1)3.已知m+n=3,mn=三分之二,求m^2+(n-mn)^2+2m(n-mn)的值

来源:学生作业帮助网 编辑:作业帮 时间:2024/05/01 14:43:50

1.1-x+4分之x^22.(x-y)^2-4(x-y-1)3.已知m+n=3,mn=三分之二,求m^2+(n-mn)^2+2m(n-mn)的值
1.1-x+4分之x^2
2.(x-y)^2-4(x-y-1)
3.已知m+n=3,mn=三分之二,求m^2+(n-mn)^2+2m(n-mn)的值

1.1-x+4分之x^22.(x-y)^2-4(x-y-1)3.已知m+n=3,mn=三分之二,求m^2+(n-mn)^2+2m(n-mn)的值
1.1-x+4分之x^2
=(1-x/2)^2
2.(x-y)^2-4(x-y-1)
=(x-y)^2-4(x-y)+4
=(x-y-2)^2
m^2+(n-mn)^2+2m(n-mn)
=(m+n-mn)^2
=(3-2/3)^2
=(7/3)^2
=49/9

1.1-x+4分之x^2
=(1-x/2)^2
2.(x-y)^2-4(x-y-1)
=(x-y)^2-4(x-y)+4
=(x-y-2)^2
3.因为m+n=3,mn=2/3
所以m^2+(n-mn)^2+2m(n-mn)
=m^2+2m(n-mn)+(n-mn)^2
=(m+n-mn)^2
=(3-2/3)^2
=(7/3)^2
=49/9

解1题:
原式=1²-2×1×(x/2)²
=(1-x/2)²
2题:
原式=(x-y)²-4(x-y)+4
=(x-y)²-2(x-y)×2+2²
=(x-y-2)²
3题:
m²+(n-mn)²+2m(n-mn)
=m²+2×m×(n-mn)+(n-mn)²
=(m+n-mn)²
=(3-2/3)²
=(7/3)²
=49/9