Question

数学题目。 化简。

（1）7X-[-2X-(8X-1)] （2）4(2a²b-ab²)-5(ab²+2a²b)

(3) 6xy-[(2X²+5xy-3y²)-(x²-3xy+y²)]

Answer 1

7X-[-2X-(8X-1)] =7x-[-2x-8x+1]=7x+2x+8x-1=17x-1
4(2a²b-ab²)-5(ab²+2a²b) =8a^2b-4ab^2-5ab^2-10a^2b=-2a^2b-9ab^2
6xy-[(2X²+5xy-3y²)-(x²-3xy+y²)]=6xy-[2x^2+5xy-3y^2-x^2+3xy-y^2]=6xy-[x^2+8xy-4y^2]=14xy-x^2+4y^2
x^2为X方 y^2为y方

Answer 2

（1）7X-[-2X-(8X-1)]=7x-(-2x-8x+1)=7x+2x+8x-1=17x-1
（2）4(2a²b-ab²)-5(ab²+2a²b) =8a²b-4ab²-5ab²-10a²b= -2a²b-9ab²
(3) 6xy-[(2X²+5xy-3y²)-(x²-3xy+y²)]=6xy-(2X²+5xy-3y²-x²+3xy-y²)=6xy-(X²+8xy-4y²)=4y²-2xy-X²