System of equations by elimination and substitution

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onmyown
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System of equations by elimination and substitution

Postby onmyown » Mon Jan 31, 2011 8:43 pm

Can someone please help me solve this system of equation by elimination and/or substitution. I'm specifically looking for a demonstration of this format of a system being solved by elimination and/or substitution.
I only get how to do systems that are in the form of y=x+a y=x-b and etc. i.e. where the variables are on the same side of both the equations.

Here is the system I'm trying to solve by elimination, where the variables are on different sides of the equation:
y=x+5
x+y=95

I can show you my attempts if you would like.

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stapel_eliz
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Postby stapel_eliz » Mon Jan 31, 2011 11:27 pm

onmyown wrote:I only get how to do systems that are in the form of y=x+a y=x-b and etc. i.e. where the variables are on the same side of both the equations.

Ah. So you need to learn how to solve, for instance, the second equation you posted for "y=". To learn how to do this, try this lesson.

Note: To solve the posted system by substitution, rather than elimination (by getting all the variables "lined up" in the specified way), just substitute! You have "y = (something)" in one equation and another equation which contains "y". Plug the "(something)" from the first equation in place of "y" in the second equation, and solve. Etc, etc. :wink:

onmyown
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Re:

Postby onmyown » Tue Feb 01, 2011 1:02 am

stapel_eliz wrote:
onmyown wrote:I only get how to do systems that are in the form of y=x+a y=x-b and etc. i.e. where the variables are on the same side of both the equations.

Ah. So you need to learn how to solve, for instance, the second equation you posted for "y=". To learn how to do this, try this lesson.

Note: To solve the posted system by substitution, rather than elimination (by getting all the variables "lined up" in the specified way), just substitute! You have "y = (something)" in one equation and another equation which contains "y". Plug the "(something)" from the first equation in place of "y" in the second equation, and solve. Etc, etc. :wink:



THANKS! I got it. Can't believe I didn't catch on to that before


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