SOLUTION: squareroot x+20-x=0 not sure what to do for this problem. Which x do you get ride of first the positive or negetive?

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Question 146673: squareroot x+20-x=0
not sure what to do for this problem. Which x do you get ride of first the positive or negetive?
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
sqrt%28x%29%2B20-x=0
You might mean sqrt%28x%2B20%29-x=0
I'll do this one:
sqrt%28x%29%2B20-x=0
sqrt%28x%29=+x-20
Square both sides
x+=+x%5E2+-40x+%2B+400
Put in quadratic form
x%5E2+-41x+%2B+400+=+0
Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 1x%5E2%2B-41x%2B400+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%28-41%29%5E2-4%2A1%2A400=81.

Discriminant d=81 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--41%2B-sqrt%28+81+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-41%29%2Bsqrt%28+81+%29%29%2F2%5C1+=+25
x%5B2%5D+=+%28-%28-41%29-sqrt%28+81+%29%29%2F2%5C1+=+16

Quadratic expression 1x%5E2%2B-41x%2B400 can be factored:
1x%5E2%2B-41x%2B400+=+%28x-25%29%2A%28x-16%29
Again, the answer is: 25, 16. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B-41%2Ax%2B400+%29