Solving system of equaton by elemination?? help?

Question

i hate math but i have h.w nd i need help...

x+y=5

3x-y=7

...........nd do ya know any web sit that i can get help.. thank you..

Answer 1

There probably aren't any websites that give you the answer to this specific problem, but it's sorta easy.

*I'm not good at explaining so I'll just solve it*

x+y=5

3x-y=7

y=5-x

3x-(5-x)=7

3x-5+x=7

3x+x=12

4x=12

x=3

Okay, we found the x. Now we find y by plugging x into either one of the equations.

x+y=5

(3)+y=5

y=2

The answer is x=3, y=2

Answer 2

1° x+y=5

2° 3x-y=7

by elimination:

x+y=5

3x-y=7 add

-----------------

4x+0=12

x=12/4=3

3+y=5

y=5-2=3

by substitution:

1°  x=5-y

2°  3(5-y)-y=7

solve for y.:

15-3y-y=7

-4y= -8

divide for  -4:

y= -8/-4

y=2

substitution:

x=5-2=3

Answer 3

You also may want to look into help with your English...

Answer 4

I'm not sure of any web sites that offer direct help on math problems, but I think I can offer a little bit of help on solving by elimination.

In solving a system of equations by elimination, you add two equations together in such a way that you eliminate one of the variables. This is accomplished by multiplying one equation by a number such that a given variable has the same number with opposite signs in front.

For example, the two equations you have are already in that form for 'y'; you have both a +y and a -y. So, you can add the equations together directly, as below:

x+3x+y-y=5+7

or

x+3x=12

I'm sure you can solve for 'x' from there, and then you can plug that 'x' value back into one of the original equations to solve for 'y'.

Typically, you won't have such a simple setup however. Sometimes you may have a situation like this:

x + 3y = 10

5x-y = 2

In which case you would need to multiply through by either 3 on the bottom equation (to eliminate 'y') or -5 on the top equation (to eliminate 'x'). After that point it solves the same, below eliminates 'x':

-5x + 5x + -15y + -y = -50+2

-16y = -48

y=3

Hope this helps!