Question

Can someone please explain to me how to solve the linear system using elimination? I would appreciate it!

Equation:
4x-y=5
4x+4y=-4

Answer 1

you can multiply one of the equation by a negative so you can cancel out the 4x

Answer 2

do you know how to do it?

Answer 3

K !
In the system if we want ti find x or y first should chose one of them first and another in second .
So should sum them and before that should do the work can delete one of the x s or y s .
So should to make Symmetric from them .
And in your equation find y is easyer caz we have 4x and 4x .
So if we multiply one of the equations on -1 can have -4x and if sum -4x and 4x just have y .
Look :(chose one of them to multiply on -1)
-1(4x-y=5)=-4x+y=-5
4x+4y=-4
Sum them :
-4x+4x+y+4y=-5-4
have : 5y=-9
y = -9/5
Got it ?
@justintaylor
By the way welcome in open study !

Answer 4

Use the first equation to minus the second one in order to eliminate x.
4x-y-(4x+4y)=5-(-4)
4x-y-4x-4y=5+4
-5y=9
y=-9/5.

Now we get y, so it is easy to get x.
4x-(-9/5)=5
4x=5-9/5
4x=25/5-9/5
4x=16/5
x=16/20
x=4/5

Thus,
x=4/5
y=-9/5

If you have any more questions, I will be glad to answer them for you.

Answer 5

take a look
very detailed
great examples
1) http://www.youtube.com/watch?v=y49duU5LeGQ
2) http://www.youtube.com/watch?v=6N73_lhZG9s

Answer 6

here is an easy method, look at the equations.... y is negative in the 1st and positive in the 2nd.

so eliminate y

multiply the 1st equation by 4 and add to the 2nd equation


16x -4y = 20
4x +4y = -4
--------------
20x = 16

solve for x

when you get x substitute into either equation to find y.

always look at the equations and decide which is the easier letter to eliminate

I chose y because of opposite signs

while everyone else chose x...

I'll let you decide

hope this helps and makes sense