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)+
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![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)+](/uploads/image/z/2660583-39-3.jpg?t=%E5%88%9D%E4%B8%80%E4%B8%8A%E5%AD%A6%E6%9C%9F%E6%95%B0%E5%AD%A6%E5%90%88%E5%B9%B6%E5%90%8C%E7%B1%BB%E9%A1%B9%E4%B8%8E%E5%8C%96%E7%AE%80%E6%B1%82%E5%80%BC%E8%A6%81%E6%B1%82%E6%9C%89%E8%BF%87%E7%A8%8B2x%26%23178%3By%26%23179%3B%2B%EF%BC%88-4x%26%23178%3By%26%23179%3B%EF%BC%89-%EF%BC%88-3x%26%23178%3By%26%23179%3B%EF%BC%89214a%2B47a%2B53a117x%2B138x-38x%EF%BC%88x-1%EF%BC%89-%EF%BC%882x%2B1%EF%BC%893%EF%BC%88x-2%EF%BC%89%2B2%EF%BC%881-2x%EF%BC%89%EF%BC%888xy-3y%26%23178%3B%EF%BC%89-5xy-2%EF%BC%883xy-2x%26%23178%3B%EF%BC%89%EF%BC%88a%2Bb-c%EF%BC%89%2B)
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