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Question 304131: solve for x: x2 = 2x (x square = 2x)
you can solve this 3 ways, which one is right and why.
1) Take the square root of both sides, which give you x= (sq root) of 2x
2) Divide both sides by x, which gives x = 2
3) or move the 2x over and factor. (x-0)(x-2)
Secondly, when you factor this problem, how come the sum of the terms doesn't add up to 2x as the FOIL method says.
Answer by dabanfield(803)   (Show Source):
You can put this solution on YOUR website! solve for x: x2 = 2x (x square = 2x)
you can solve this 3 ways, which one is right and why.
1) Take the square root of both sides, which give you x= (sq root) of 2x
2) Divide both sides by x, which gives x = 2
3) or move the 2x over and factor. (x-0)(x-2)
Secondly, when you factor this problem, how come the sum of the terms doesn't add up to 2x as the FOIL method says.
The first way still leaves you with x = +sqrt(2x) or x = -sqrt(2x) so you haven't completely isolated x.
The second way is fine except you are assuming x is not zero or you couldn't divide both sides by it.
The third way is correct and gives you the solution x = 0 and x = 2.
Using FOIL on (x-0)*(x-2) = 0 you have x*x - x*2 - 0*x + (0*2) = 0.
x^2 - 2x - 0 + 0 = 0
x^2 - 2x = 0
x2 = 2x
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