Question 503317: 2x+5y=-16
6x-9y=-48
I could not even figure out how to do this i tried to solve for x at first for the first one and took a wild guess and got x= -36/17 and y= 176/17 and it was in correct
Answer by Maths68(1474)   (Show Source):
You can put this solution on YOUR website! By substitution method
2x+5y=-16 ...................(1)
6x-9y=-48 ...................(2)
Take (1)
2x+5y=-16
2x=-16-5y
x=(-16-5y)/2
Put the above value of x in (2)
6((-16-5y)/2))-9y=-48
3(-16-5y)-9y=-48
-48-15y-9y=-48
-15y-9y=-48+48
-15y-9y=-48+48
-24y=0
Divide by -24 both sides of above equation
-24y/-24=0/-24
y=0
Put the value of y in (1), we have
2x+5y=-16
2x+5(0)=-16
2x+0=-16
2x=-16
Divide by 2 both sides of the above equation
2x/2=-16/2
x=-8
Solution Set (-8, 0)
By Elimination method
Multiply (1) by 6 and (2) by -2, we have
(6)(2x+5y=-16)
(-2)(6x-9y=-48)
12x+30y=-96 .............(3)
-12x+18=96 ..............(4)
Add (3) and (4)
12x+30y=-96
-12x+18=96
--------------------
48y=0
Divide by 48 both sides of the above equation
48y/48=0/48
y=0
Put the value of y (2)
6x-9y=-48........(2)
6x-9(0)=-48
6x=-48
Divide by 6 both sides of the above equation
6x/6=-48/6
x=-8
Solution Set (-8, 0)
Check
Put the values of x and y in any of two equations (1) or (2)
First equation (1)
2x+5y=-16
2(-8)+5(0)=-16
-16+0=-16
-16=-16
Now equation (2)
6x-9y=-48 .......(2)
6(-8)-9(0)=-48
-48-0=-48
-48=-48
|
|
|
