SOLUTION: Hi, I have done this problem in solving equation: 2^2 � x � 1 = 0 This is how I did the problem Factor the equation: (2x + 1) (x � 1) = 0 Factor separately to equal 0: 2x + 1=

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Question 141026: Hi, I have done this problem in solving equation:
2^2 � x � 1 = 0
This is how I did the problem
Factor the equation: (2x + 1) (x � 1) = 0
Factor separately to equal 0: 2x + 1= 0 x � 1 = 0
2x = -1 x = 1
x = - �
My question is how to check the answer, and to go back to original equation?
I hope some one can help me please I am not sure about how to go back to the original equation. Thank you very much.

Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website!
2x^2 � x � 1 = 0
2x^2-2x+x-1 = 0
2x(x-1)+(x-1) = 0
(x-1)(2x+1) = 0
x-1 = 0 or 2x+1 = 0
x = 1 or x = -1/2
----------------------
Checking:
x=1:
2*1^2 - 1 -1 = 0
2-1-1 = 0
0=0
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x=-1/2
2(-1/2)^2-(-1/2)-1 = 0
2(1/4) + 1/2 - 1 = 0
1/2 + 1/2 - 1 = 0
1 - 1 = 0
0 = 0
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Cheers,
Stan H.