已知6x-1=2,2y+3=5,求（5x²y+5xy-7y)-(4x²y+5xy-7x)的值.好的追分哦!_数学解答

已知6x-1=2,2y+3=5,求（5x²y+5xy-7y)-(4x²y+5xy-7x)的值.好的追分哦!

人气：282 ℃　时间：2020-03-26 09:51:33

解答

6x-1=2,x=1/2
2y+3=5,y=1
(5x²y+5xy-7y)-(4x²y+5xy-7x)
=x²y-7y+7x
=1/4*1-7*1+7*1/2
=(1-4*7-7*2)/4
=-13/4