1.用代入法解 5a+5b-15=0① 3a+8b-1=0②

问题描述:

1.用代入法解 5a+5b-15=0① 3a+8b-1=0②
2.用加减法解(1)6x+5y=7① 9x+4y=14②
(2)x/3-y/4=1① 3x-4y=2②

5a+5b-15=0 ①3a+8b-1=0 ②由①得a+b=3a=3-b ③把③代入②得3(3-b)+8b-1=05b=-8b=-8/5把b=-8/5代入③得a=3-b=23/5∴{a=23/5,b=-8/5(1)6x+5y=7 ①9x+4y=14 ②①×4得:24x+20y=28 ③②×5得:45x+20y=70 ④④—③...