1、计算:①(4X²-5xy)-(1/3y²+2x²)+2(5xy-1/4y²-1/12y²)2、先化简,再求值:①(2a²-b)-(a²-4b)-(b+c),其中a=1/3,b=1/2,c=1②2(x的立方-2y²)-(x-2y)-(x-3y²+2x的
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/02 16:45:32
![1、计算:①(4X²-5xy)-(1/3y²+2x²)+2(5xy-1/4y²-1/12y²)2、先化简,再求值:①(2a²-b)-(a²-4b)-(b+c),其中a=1/3,b=1/2,c=1②2(x的立方-2y²)-(x-2y)-(x-3y²+2x的](/uploads/image/z/1991089-1-9.jpg?t=1%E3%80%81%E8%AE%A1%E7%AE%97%EF%BC%9A%E2%91%A0%EF%BC%884X%26%23178%3B-5xy%EF%BC%89-%EF%BC%881%2F3y%26%23178%3B%2B2x%26%23178%3B%EF%BC%89%2B2%EF%BC%885xy-1%2F4y%26%23178%3B-1%2F12y%26%23178%3B%EF%BC%892%E3%80%81%E5%85%88%E5%8C%96%E7%AE%80%2C%E5%86%8D%E6%B1%82%E5%80%BC%EF%BC%9A%E2%91%A0%EF%BC%882a%26%23178%3B-b%EF%BC%89-%EF%BC%88a%26%23178%3B-4b%EF%BC%89-%EF%BC%88b%2Bc%EF%BC%89%2C%E5%85%B6%E4%B8%ADa%3D1%2F3%2Cb%3D1%2F2%2Cc%3D1%E2%91%A12%EF%BC%88x%E7%9A%84%E7%AB%8B%E6%96%B9-2y%26%23178%3B%EF%BC%89-%EF%BC%88x-2y%EF%BC%89-%EF%BC%88x-3y%26%23178%3B%2B2x%E7%9A%84)
1、计算:①(4X²-5xy)-(1/3y²+2x²)+2(5xy-1/4y²-1/12y²)2、先化简,再求值:①(2a²-b)-(a²-4b)-(b+c),其中a=1/3,b=1/2,c=1②2(x的立方-2y²)-(x-2y)-(x-3y²+2x的
1、计算:
①(4X²-5xy)-(1/3y²+2x²)+2(5xy-1/4y²-1/12y²)
2、先化简,再求值:
①(2a²-b)-(a²-4b)-(b+c),其中a=1/3,b=1/2,c=1
②2(x的立方-2y²)-(x-2y)-(x-3y²+2x的立方),其中X=-3,y=-2
1、计算:①(4X²-5xy)-(1/3y²+2x²)+2(5xy-1/4y²-1/12y²)2、先化简,再求值:①(2a²-b)-(a²-4b)-(b+c),其中a=1/3,b=1/2,c=1②2(x的立方-2y²)-(x-2y)-(x-3y²+2x的
1、计算
①(4X²-5xy)-(1/3y²+2x²)+2(5xy-1/4y²-1/12y²)
=4x^2-5xy-1/2y^2-2x^2+10xy-1/2y^2-1/6y^2
=4x^2-2x^2+10xy-5xy-1/2y^2-1/3y^2-1/6y^2
=2x^2+5xy-y^2
2、先化简,再求值:
①(2a²-b)-(a²-4b)-(b+c),其中a=1/3,b=1/2,c=1
=2a^2-b-a^2+4b-b-c
=a^2+2b-c
=(1/3)^2+2*1/2-1
=1/9+1-1
=1/9
②2(x的立方-2y²)-(x-2y)-(x-3y²+2x的立方),其中X=-3,y=-2
=x^3-2y^2-x+2y-x+3y^2-2x^3
=-x^3+y^2-2x+2y
=-(-3)^3+(-2)^2-2*(-3)+2*(-2)
=-27+4+6-4
=-21
1.
2x^2+5xy-y^2
2.
a^2+2b-c 1/9
-y^2-2x+2y -2