作业帮几道初一代数解答题1.已知a+b=7,ab=6,求a²b+ab²的值.2.已知x²-y²=-1,x+y=½,求x-y的值.3.已知：4m+n=90,2m-3n=10,求（m+2n)²-(3m-n）²的值.加上过程哦~~~~谢了~~~~~~~~~~~~
来源：学生作业帮助网 编辑：作业帮 时间：2024/05/12 15:14:36
几道初一代数解答题1.已知a+b=7,ab=6,求a²b+ab²的值.2.已知x²-y²=-1,x+y=½,求x-y的值.3.已知：4m+n=90,2m-3n=10,求（m+2n)²-(3m-n）²的值.加上过程哦~~~~谢了~~~~~~~~~~~~
几道初一代数解答题
1.已知a+b=7,ab=6,求a²b+ab²的值.
2.已知x²-y²=-1,x+y=½,求x-y的值.
3.已知：4m+n=90,2m-3n=10,求（m+2n)²-(3m-n）²的值.
加上过程哦~~~~谢了~~~~~~~~~~~~
几道初一代数解答题1.已知a+b=7,ab=6,求a²b+ab²的值.2.已知x²-y²=-1,x+y=½,求x-y的值.3.已知：4m+n=90,2m-3n=10,求（m+2n)²-(3m-n）²的值.加上过程哦~~~~谢了~~~~~~~~~~~~
a²b+ab²=ab(a+b)=42
x-y=(x²-y²）/x+y=-2
3.4m+n=90,n=90-4m 因为2m-3n=10,2m-3(90-4m)=10 得m=20所以n=10
（m+2n)²-(3m-n）²=-900
1.原式=ab(a+b)=6*7=42
2. x²-y²=(x+y)(x-y)=-1
所以x-y=-1/(x+y)=-2
3.（m+2n)²-(3m-n）²
=(m+2n+3m-n)(m+2n-3m+n)
=(4m+n)(-2m+3n)
=-(4m+n)(2m-3n)
=-90*10
=-900
1.a2b+ab2=ab(a+b)=42;
2.x-y=(x2-y2)/(x+y)=-2;
3.m+2n=1/2(4m+n)-1/2(2m-3n)=40;
3m-n=1/2(4m+n)+1/2(2m-3n)=50;
所以为:-900