Question

用加减法减下列方程.1.2x+5y=12,2.3x-2y=1,3.3(x-1)=4y +1 2x+3y=6.6x+4y=

Answer 1

2x+5y-(2x+3y)=12-6 ②

5y-3y=6

2y=6

y=3 ①

将 ①代入②得

x=-3/2

3x-2y+(6x+4y)/2=1+10/2 ②

3x+3x=1+5

6x=6

x=1①

将①代入②得

y=1

3(x-1)-3*(x+1)=4y+1-5*(y-i)*3 ②

3x-3-3x-3=4y+1-15y+15

11y=22

y=2①

将①代入②得

x=4