# system of equations using substitution method

• Feb 26th 2008, 09:06 AM
system of equations using substitution method
How would I solve this problem using the substitution method. Any help woud be greatly appreciated. :~}

x=y+3
4x+y=2
• Feb 26th 2008, 09:31 AM
Im not sure if i did it right
4(y+3)+y=2

4y+12+y=2
x=y+3
5y+12=2 (-12 from both sides)
5y=-10 (/ both sides by 5)
y=-2

Then I found x
x=-2+3
x=1
• Feb 26th 2008, 09:48 AM
mathceleb
Assistance
2 Unknowns by Substitution Calculator

Enter 4x+y=2 for Equation 1 and x-y=3 for Equation 2 and Press Calculate.

Solution: (x, y) = (1, -2)

if you want to see the opposite way of substitution method, switch equation 1 and equation 2 in the entry boxes. :-)

Sometime later this week, I'll clean up the math portion to not show denominators of 1 and coefficients of 1. It looks like you missed a sign. Look at the section where it says:

"Now, group like terms by getting the y variables on one side of the equation and the constants on the other side:"

I hope this helps, let me know if you have questions.
• Feb 26th 2008, 09:56 AM
How would i enter this into my calculator? I see an x button but no y button
• Feb 26th 2008, 10:00 AM
bobak
Quote:

Originally Posted by mathceleb
2 Unknowns by Substitution Calculator

Enter x-y=3 for Equation 1 and 4x+y=2 and Press Calculate.

(x, y) = (1, -2)

if you want to see the opposite way of substitution method, switch equation 1 and equation 2 in the entry boxes. :-)

I dont think it is appropriate to suggest this sort of method for what is a very easy problem.

Quote:

4(y+3)+y=2

4y+12+y=2
x=y+3
5y+12=2 (-12 from both sides)
5y=-10 (/ both sides by 5)
y=-2

Then I found x
x=-2+3
x=1
(Clapping) Keep up the good work. ( and possibly change your username (Wink) )
• Feb 26th 2008, 10:09 AM
I wish i could change my user name but i am not that good at math i do all right on the home work and stuff but when the tests come around i forget how to solve each individual problem i use one type of method on the wronge type of problem and get totaly confused lol
• Feb 26th 2008, 10:14 AM
mathceleb
Quote:

Originally Posted by bobak
I dont think it is appropriate to suggest this sort of method for what is a very easy problem.

I thought it would help to show him where he missed his sign. I thought sites where you did not sell anything were acceptable. If they are not, let me know and I won't post anymore.
• Feb 26th 2008, 10:56 AM
topsquark
Quote:

Originally Posted by mathceleb
I thought it would help to show him where he missed his sign. I thought sites where you did not sell anything were acceptable. If they are not, let me know and I won't post anymore.

There is nothing wrong with your posting a site contains a program that will give students their answers. However the main aim of this site is to teach how to do the problems, not simply show them, and a suggestion like this will likely bend a few noses.

-Dan