初一上学期数学合并同类项与化简求值要求有过程2x²y³+(-4x²y³)-(-3x²y³)214a+47a+53a117x+138x-38x(x-1)-(2x+1)3(x-2)+2(1-2x)(8xy-3y²)-5xy-2(3xy-2x²)(a+b-c)+

来源:学生作业帮助网 编辑:作业帮 时间:2024/03/28 23:03:31
初一上学期数学合并同类项与化简求值要求有过程2x²y³+(-4x²y³)-(-3x²y³)214a+47a+53a117x+138x-38x(x-1)-(2x+1)3(x-2)+2(1-2x)(8xy-3y²)-5xy-2(3xy-2x²)(a+b-c)+

初一上学期数学合并同类项与化简求值要求有过程2x²y³+(-4x²y³)-(-3x²y³)214a+47a+53a117x+138x-38x(x-1)-(2x+1)3(x-2)+2(1-2x)(8xy-3y²)-5xy-2(3xy-2x²)(a+b-c)+
初一上学期数学合并同类项与化简求值要求有过程
2x²y³+(-4x²y³)-(-3x²y³)
214a+47a+53a
117x+138x-38x
(x-1)-(2x+1)
3(x-2)+2(1-2x)
(8xy-3y²)-5xy-2(3xy-2x²)
(a+b-c)+(b+c-a)+(c+a-b)
已知m=3x²-2xy+y² ,n=2x²+xy-3y²
其中x=1,y=3(先化简再求值)
求m-n,m+n

初一上学期数学合并同类项与化简求值要求有过程2x²y³+(-4x²y³)-(-3x²y³)214a+47a+53a117x+138x-38x(x-1)-(2x+1)3(x-2)+2(1-2x)(8xy-3y²)-5xy-2(3xy-2x²)(a+b-c)+
2 x²y³+(-4x²y³)-(-3x²y³)
=2x²y³-4x²y³+3x²y³
=x²y³
214a+47a+53a
=(214+47+53)a
=314a
117x+138x-38x
=(117+138-38)x
=17x
(x-1)-(2x+1)
=x-1-2x-1
=-x-2
3(x-2)+2(1-2x)
=3x-6+2-4x
=-x-4
(8xy-3y²)-5xy-2(3xy-2x²)
=8xy-3y²-5xy-6xy+4x²
=-3y²-3xy+4x²
(a+b-c)+(b+c-a)+(c+a-b)
=a+b-c+b+c-a+c+a-b
=a+b+c
已知m=3x²-2xy+y² ,n=2x²+xy-3y²
其中x=1,y=3(先化简再求值)
求m-n,m+n
m-n=3x²-2xy+y²-(2x²+xy-3y²)
=3x²-2xy+y²-2x²-xy+3y²
=x²-3xy+4y²
当x=1,y=3时
原式=1-9+36=28
m+n=3x²-2xy+y²+2x²+xy-3y²
=5x²-xy-2y²
当x=1,y=3时
原式=5-3-18
=-16