SOLUTION: I am having trouble solving this equation by either using the quadratic formula, by factoring or by completing the square.. 3x^2=15x+10 i have come up with the answer of x=15+-

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons -> SOLUTION: I am having trouble solving this equation by either using the quadratic formula, by factoring or by completing the square.. 3x^2=15x+10 i have come up with the answer of x=15+-      Log On


   

Question 602255: I am having trouble solving this equation by either using the quadratic formula, by factoring or by completing the square..
3x^2=15x+10
i have come up with the answer of x=15+- square root of 105/6 is this correct?
email is stonewoodfarms87@aol.com
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
solving this equation by either using the quadratic formula, by factoring or by completing the square..
3x^2 = 15x + 10
completing the square
3x^2 - 15x + ____ = 10
We want the coefficient of x^2 to be 1, divide thru by 3
x^2 - 5x + ____ = 10%2F3
find the value to complete the square: (5/2)^2 = 25/4, add to both sides
x^2 - 5x + 25%2F4 = 10%2F3 + 25%2F4
;
(x - 5%2F2)^2 = 40%2F12 + 75%2F12
:
(x - 5%2F2)^2 = 115%2F12
:
(x - 5%2F2) = +/- sqrt%28115%2F12%29
extract he square root of 1/4
x = 5%2F2 + 1%2F2sqrt%28115%2F3%29 = %285%2Bsqrt%28115%2F3%29%29%2F2
and
x = %285-sqrt%28115%2F3%29%29%2F2