SOLUTION: the question is: solve the quadratic equation by completing the square: x^2-20x=0 x^2-20x+(20/2)^2 = (20/2)^2 (sqrt x - sqrt 10^2)^2 = sqrt 100 x-10 = +- 10 x-10=10

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: the question is: solve the quadratic equation by completing the square: x^2-20x=0 x^2-20x+(20/2)^2 = (20/2)^2 (sqrt x - sqrt 10^2)^2 = sqrt 100 x-10 = +- 10 x-10=10       Log On


   

Question 207259: the question is: solve the quadratic equation by completing the square:
x^2-20x=0
x^2-20x+(20/2)^2 = (20/2)^2
(sqrt x - sqrt 10^2)^2 = sqrt 100
x-10 = +- 10
x-10=10 x-10 =-10
x=20 x=0
I am checking to make sure I did the work correctly, this isn't from a textbook so I don't have a page # or anything to reference too.
Thank you for your help.
Found 3 solutions by solver91311, RAY100, Edwin McCravy:
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


Same as Question 207261. Your notation is whacked but you did the problem correctly.


John

Answer by RAY100(1637) About Me  (Show Source):
You can put this solution on YOUR website!
x^2 -20x =0
.
x^2 -20x +(20/2)^2 = (20/2)^2
.
x^2 -20x +100 = 100
.
(x-10)^2 =100
.
take sqrt of both sides
.
+/- (x-10) = +/- 10
.
(x-10) =10,,,x=20,,check,,(20)^2 -20(20)=0,,400-400=0,,ok
.
(x-10)= -10,,,x=0,,check,,(0)^2 -20(0)=0,,,ok
.
-x+10=10,,x=0,,,check,,ok
.
-x+10=-10,,x=20,,check,,ok
.
Therefore,,,x=0,20






Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
the question is: solve the quadratic equation by completing the square: 

You did it right but your notation is bad.

x%5E2-20x=0

x%5E2-20x%2B%2820%2F2%29%5E2+=+%2820%2F2%29%5E2

x%5E2-20x%2B10%5E2%29+=+%2810%29%5E2

x%5E2-20x%2B100%29+=+100

%28x-10%29%28x-10%29+=+100

%28x-10%29%5E2+=+100

sqrt%28%28x-10%29%5E2%29=+%22%22%2B-sqrt%28100%29

x-10=±10

Using the +

x-10=10
x=20

Using the -

x-10=-10
x=0

Edwin