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 dont 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
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:
- Necessary Math HELp - helper, Thursday, January 13, 2011 at 9:32pm
correct, the answer is (-4, 3)
Answer This Question
More Related Questions
- science - Writing variables and hypothesses What about them? i dont even ...
- Algebra - Solve each literal equations for the indicated variable D = C - s/n ( ...
- 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...
- Statistics - Hello, I have a question concerning predictivity/ or R squared of ...
- science - from the balanced equation 4NH3 +7O2 - 4NO2 + 6H2O. How many grams of ...