Help with Solution by Elimination

Quadratic equations and inequalities, variation equations, function notation, systems of equations, etc.
bellerum23
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Joined: Thu Oct 24, 2013 5:13 pm
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Help with Solution by Elimination

Postby bellerum23 » Tue Nov 05, 2013 6:38 pm

Solve each system by addition, if possible

Having trouble understanding this.

x + y = 1
x - y = 7

Do I add it together like this:

x + y = 1
x - y = 7
--------------
2x = 8

Then, should I divide it like this:

8/2x = 4


My professor at the college went too fast for me to understand how to do Solution by Eliminations.

FWT
Posts: 119
Joined: Sat Feb 28, 2009 8:53 pm

Re: Help with Solution by Elimination

Postby FWT » Wed Nov 06, 2013 1:10 am

bellerum23 wrote:Solve each system by addition, if possible

Having trouble understanding this.

My professor at the college went too fast for me to understand how to do Solution by Eliminations.

Your steps look fine to me. You can check by plugging your answer back into the system and making sure it works in both eqns. You can learn how to do it here.

Marvin Kalngan
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Joined: Sun Dec 15, 2013 3:04 am
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Re: Help with Solution by Elimination

Postby Marvin Kalngan » Sun Dec 15, 2013 3:08 pm

x + y = 1
x - y = 7
--------------
2x = 8 >>>>> y was eliminated

Then, divide both sides of the equation by 2 to solve for x

2x/2 = 8/2
x = 4

substitute the value of x in any of the two equations to solve for y

x + y = 1
4 + y = 1
y = 1 - 4
y = -3

x - y = 7
4 - y = 7
4 - 7 = y
-3 = y


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