(1)已知m、n为系数,且mx^2+2xy-x与3x^2-2nxy+3y的差不含二次项,求m^2-3n的值.(2)已知a-2b=-3,求3(a-b)-3(3b-a+1)的值.
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/08 13:22:32
![(1)已知m、n为系数,且mx^2+2xy-x与3x^2-2nxy+3y的差不含二次项,求m^2-3n的值.(2)已知a-2b=-3,求3(a-b)-3(3b-a+1)的值.](/uploads/image/z/5939846-62-6.jpg?t=%EF%BC%881%EF%BC%89%E5%B7%B2%E7%9F%A5m%E3%80%81n%E4%B8%BA%E7%B3%BB%E6%95%B0%2C%E4%B8%94mx%5E2%2B2xy-x%E4%B8%8E3x%5E2-2nxy%2B3y%E7%9A%84%E5%B7%AE%E4%B8%8D%E5%90%AB%E4%BA%8C%E6%AC%A1%E9%A1%B9%2C%E6%B1%82m%5E2-3n%E7%9A%84%E5%80%BC.%EF%BC%882%EF%BC%89%E5%B7%B2%E7%9F%A5a-2b%3D-3%2C%E6%B1%823%EF%BC%88a-b%EF%BC%89-3%283b-a%2B1%29%E7%9A%84%E5%80%BC.)
x͒O0-[ O1[^xA D" bƈxOv}Jcvp/f<9t!x"\r/;D `#BhAaYIT_Ol=ZZ)cdE8_̣"A֠E "' Y8b-`Dn/+uZ҂FzKQdIWܨ8zJ7%Xt5ddjaH:ݤ[ !6\EYYZgflf8|ȏ&CoA%-.Sp@|j{leiX
_^ÏBYm)ʧ *pjߙ\ X!
(1)已知m、n为系数,且mx^2+2xy-x与3x^2-2nxy+3y的差不含二次项,求m^2-3n的值.(2)已知a-2b=-3,求3(a-b)-3(3b-a+1)的值.
(1)已知m、n为系数,且mx^2+2xy-x与3x^2-2nxy+3y的差不含二次项,求m^2-3n的值.
(2)已知a-2b=-3,求3(a-b)-3(3b-a+1)的值.
(1)已知m、n为系数,且mx^2+2xy-x与3x^2-2nxy+3y的差不含二次项,求m^2-3n的值.(2)已知a-2b=-3,求3(a-b)-3(3b-a+1)的值.
(mx^2+2xy-x)-(3x^2-2nxy+3y)
=(m-3)x^2+(2+2n)xy-x-3y
由于两个多项式的差不含二次项,则有
{m-3=0
2+2n=0;
解得m=3,n=-1
所以:m^2-3n=3^2-3×(-1)=9+3=12.
(2)、3(a-b)-3(3b-a+1)
=3a-3b-9b+3a-3
=6a-12b-3
=6(a-2b)-3
把a-2b=-3代入,得:
原式=6×(-3)-3=-21.
1.mx^2+2xy-x-(3x^2-2nxy+3y)=(m-3)x^2+(2+2n)xy-x-3y
因为mx^2+2xy-x与3x^2-2nxy+3y的差不含二次项
m-3==0,2+2n=0
m^2-3n=9+3=12
2.3(a-b)-3(3b-a+1)
=6a-6b-3
=-21