SOLUTION: Please solve this problem ASAP. I have a test tomorrow and I am doing extra practice to prepare. I completed this problem, but I am unsure if I did it correctly. Thanks in advance

Algebra ->  Square-cubic-other-roots -> SOLUTION: Please solve this problem ASAP. I have a test tomorrow and I am doing extra practice to prepare. I completed this problem, but I am unsure if I did it correctly. Thanks in advance       Log On


   

Question 746932: Please solve this problem ASAP. I have a test tomorrow and I am doing extra practice to prepare. I completed this problem, but I am unsure if I did it correctly. Thanks in advance for helping me. Complete the square of the following problem: 2x^2 = 4x - 5
I got the answer: x = 1 +/- i sqrt3/2
*+/- = positive negative
*sqrt = square root
*i = fake number system was used
Thanks again in advance.
Found 3 solutions by josgarithmetic, Alan3354, rothauserc:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Your solution for x does not indicate your knowing about Completing the Square. Showing some of your work for Completing the Square would be better than just showing what x is.

2x%5E2+=+4x+-+5
2x%5E2-4x%2B5=0
2%2A%28x%5E2-2x%29%2B5=0
What must be added to the rectangular expression to make the result into a square expression? You will need %282%2F2%29%5E2=1. Add 1 inside the parentheses and subtract 1%2A2=2 outside of the parentheses. From that, you have other calculations and simplifications. Your turn.

----I should include, the reason 1 will complete the square is because you have %28x%5E2-2x%29 as the "rectangular" expression and that is what you want to use in making a square trinomial, which can then be factored. The "2" used is the "b" which is generally used as %28b%2F2%29%5E2, the term which is added to Complete the Square.

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Complete the square of the following problem: 2x^2 = 4x - 5
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I think you mean solve for x by completing the square.
2x%5E2+=+4x+-+5
2x%5E2+-+4x+=+-+5
x%5E2+-+2x+=+-5%2F2
x%5E2+-+2x+%2B+1+=+-5%2F2+%2B+1+=+-3%2F2
%28x-1%29%5E2+=+-3%2F2
x-1+=+sqrt%28-3%2F2%29
x+=+1+%2B+i%2Asqrt%286%29%2F2
x+=+1+-+i%2Asqrt%286%29%2F2
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Same as your answers, I took the fraction out of the radical.

Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
we are asked to
Complete the square of the following problem: 2x^2 = 4x - 5
2x^2 - 4x = 5
x^2 - 2x = 5/2
add 1 to both sides and we get
x^2 - 2x + 1 = 5/2 + 1 and
(x-1)^2 = 7/2
x-1 = sqrt(7/2)
x = 1+sqrt(7/2) = 1 + 1.9 = 2.9
x = 1-sqrt(7/2) = 1 - 1.9 = -.9