Help with Solution by Elimination  TOPIC_SOLVED

Quadratic equations and inequalities, variation equations, function notation, systems of equations, etc.

Help with Solution by Elimination

Postby bellerum23 on 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.
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Re: Help with Solution by Elimination

Postby FWT on 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.
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Re: Help with Solution by Elimination  TOPIC_SOLVED

Postby Marvin Kalngan on 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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