SOLUTION: 4. Solve by completing the square. x^2-5x+2 I can't figure out my next step. I got as far as 1/2(-5)^2=. 2.5 is half of 5 but then what do I do?

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: 4. Solve by completing the square. x^2-5x+2 I can't figure out my next step. I got as far as 1/2(-5)^2=. 2.5 is half of 5 but then what do I do?      Log On


   

Question 62205: 4. Solve by completing the square.

x^2-5x+2
I can't figure out my next step. I got as far as 1/2(-5)^2=. 2.5 is half of 5 but then what do I do?
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Solve by completing the square:
x%5E2-5x%2B2+=+0? You left out the = so I'm presuming it was supposed to be = 0. Start by subtracting 2 from both sides.
x%5E2-5x+=+-2 Now complete the square in the x-terms by adding the square of half the x-coefficient, that's %285%2F2%29%5E2+=+25%2F4 to both sides.
x%5E2-5x%2B25%2F4+=+%2825%2F4%29-2 Factor the left sides and simplify.
%28x-5%2F2%29%5E2+=+%2825-8%29%2F4
%28x-5%2F2%29%5E2+=+17%2F4 Take the square root of both sides.
x-5%2F2+=+%28sqrt%2817%29%29%2F2 (+ or -) Finally, add 5/2 to both sides.
x+=+5%2F2%2B%281%2F2%29sqrt%2817%29 and
x+=+5%2F2-%281%2F2%29sqrt%2817%29