解方程(1) {5x+2y=2 7x-5y=34 (2){8x+3y+2=0,6x+5y+7=0 (3){x+1/3-y+2/4=0,x-3/4-y-3/3=1/12

来源:学生作业帮助网 编辑:六六作业网 时间:2024/11/24 05:41:38
解方程(1){5x+2y=27x-5y=34(2){8x+3y+2=0,6x+5y+7=0(3){x+1/3-y+2/4=0,x-3/4-y-3/3=1/12解方程(1){5x+2y=27x-5y=3

解方程(1) {5x+2y=2 7x-5y=34 (2){8x+3y+2=0,6x+5y+7=0 (3){x+1/3-y+2/4=0,x-3/4-y-3/3=1/12
解方程(1) {5x+2y=2 7x-5y=34 (2){8x+3y+2=0,6x+5y+7=0 (3){x+1/3-y+2/4=0,x-3/4-y-3/3=1/12

解方程(1) {5x+2y=2 7x-5y=34 (2){8x+3y+2=0,6x+5y+7=0 (3){x+1/3-y+2/4=0,x-3/4-y-3/3=1/12
1、5x+2y=2 ①
7x-5y=34 ②
①×5+②×2得:
25x+14x=10+68
39x=78
x=2
把x=2代入①中得:14-5y=34
-5y=20
y=-4
∴x=2
y= -4

8x+3y+2=0 ①
6x+5y+7=0 ②
①×5 得 40x +15y +10 =0
②×3 得 18x + 15y +21 =0
两式相减:22x - 11 =0
解得 x = 1/2
代入①得
4+3y+2=0
解得 y = -2
所以方程组的解为
x= 1/2
y = -2

(1)x=2 y=-4 (2)y=-2 x=1/2 (3)x=2 y=2

(1) 5x+2y=2 ①
7x-5y=34 ②
①*5+②*2 得 x=2,y=-4
(2) 8x+3y+2=0 ①
6x+5y+7=0 ②
①*5-②*3 得 x=1/2,y=-2
(3) x+1/3-y+2/4=0
x-3/4-y-3/3=1/12
无法解