數學題問?? (五分)

04(a)
x=5--1
2x+y=8--2
1代入2
2(5)+y=8
y=8-10=-2
(b)
y=x---1
3x-5y=4---2
1代入2
3x-5x=4
-2(x)=4
x=-2---3
3代入1
x=-2
05(a)
x+y=5--1
x-y=3---2
1-2
x+y-(x-y)=5-3
x+y-x+y=2
2y=2
y=1
1+2
x+y+(x-y)=5+3
x+y+x-y=8
2x=8
x=4
(b)
x-2y=-2---1
x=14---2
2y=14---3
1-2
x-2y-x=2-14
-2y=-12
y=6
1+3
x-2y+(2y)=2+14
x=16

a) x=5
2x+y=8 ---------A
Sub x=5 into A
2(5)+y=8
y=8-10
y=-2
b) y=x
3x-5y=4 ----------B
Sub y=x into B
3y-5y=4
-2y=4
y=4/-2
y=-2
--------------------------------------------
5a) x+y = 5 ----------A
x-y = 3 ---------B
A x+y=5
B x-y=3
---------------
A-B 2y=2
y=1
Sub y=1 into A
x+1=5
x=4

4(a) y = -2
(b)y = 2

5(a) x = 4
y = 1

(b) your question must have some problems... have you type it correctly?

4) x=5
2(5) + y = 8
y= -2


y=x
3x-5 (x)=4
x=-2