Posted by **Mathew** on Thursday, January 13, 2011 at 8:55pm.

2x + y = -5

3x +5y = 3

How come I have to multiply by 5 to make the y variables cancel, like what does that mean? I don't get how ur supposed to multiply like where and how? Im really stuck right now, please help:(

- Necessary Math HELp -
**helper**, Thursday, January 13, 2011 at 9:21pm
2x + y = -5

3x +5y = 3

to solve 2 equations simultaneously (at the same time), by elimination, the object is to get rid of one variable.

adding a negative to a positive equals zero, for example, 5y + -5y = 0.

So, to get rid of y in the above 1st equation, since the first equation has just "y" and the second equation has "5y", you multiply the first equation by -5 to get "-5y" so that the -5y added to 5y = 0,

Multiply the whole equation by -5

-5 (2x + y = -5) = -10x - 5y = 25

Now add the two equations together

-10x - 5y = 25

3x + 5y = 3

-7x + 0 = 28

-7x = 28

x = -4

substitute x = -4 in either equation and solve for your y value

do you understand this?

- Necessary Math HELp -
**Mathew**, Thursday, January 13, 2011 at 9:28pm
Wow helper:D

Thanks a lot buddy, I really appreciate all the time you put to help me with my question. Yeah thanks to your explanation I get it, thanks a lot:)

So here's how I substitute right?

2x+y = -5

2(-4)+y = -5

-8 +y = -5

Then I add 8 to both sides and get:

y = -3

Therefore the solution would be:

(-4,3)

- Necessary Math HELp -
**helper**, Thursday, January 13, 2011 at 9:32pm
correct, the answer is (-4, 3)

## Answer This Question

## Related Questions

- math/algebra - I have a question of how do I determine the variables when ...
- algebra - Simplify using only positive exponents. (2r^-1s^2t^0)^-2...
- math,help - okay Directions: find the following squares. Problem: ((w)-(1)/(4))^...
- bobpursley,math - about this problem , I figured it out and i did get the answer...
- Belinda, Math - Thank you I did figure it out i think: so the problem was ((w)-(...
- math - how do you solve this type of math problems that indicates to perform the...
- math - I need help solve the equation by fractions 8/(21-y) = 12/(y+19) I think ...
- help,math - simplify (x+2)/(x) divided by (x-2)/(3x) (x+2)/(x) divided by (x-2)/...
- math-calculus - 15+2y-y^2/3y^2-16y+5 (5-y)(3+y)/(3y-1)(y-5) i factor out a ...
- math - 1.make up 10 different algebraic expressions 5 of them will have a single...

More Related Questions