問2題數學題

3x+y=11.....1
-3x+2y=10....2

1-2,(3x+y)+(-3x+2y)=11+10
3y=21
y=7
Sub y=7 into 1
3x+7=11
3x=4
x=4/3

so the solution is x=4/3,y=7


2.5x-y=16 .....1

5x-3y=8 ......2

1-2, (5x-y)-(5x-3y)=16-8
2y=8
y=8/2
y=4
Sub y=4 into 1
5x-4=16
5x=16+4
5x=20
x=20/5
x=4

so th solution is x=4 ,y=4.

1) 3x + y = 11 .....(a)
-3x + 2y = 10 .....(b)
add both sides: 3y = 21 => y = 7

From (a), 6x + 2y = 22 .....(c)
subtract (b) by (c) => 9x = 12 => x = 4/3



2) 5x - y = 16 .....(a) seems you've forgot to type "= 16", right?
5x - 3y =8 .....(b)
subtract (b) by (a) => 2y = 8 => y = 4

From (a), 15x - 3y = 48 .....(c)
subtract (b) by (c) => 10x = 40 => x = 4

1. 3y=21
y=7

你第二題係咪寫漏野啊?

1. 3y=21
y=7

你第二題係咪寫漏野啊?