• October 14th 2009, 09:36 PM
Mist
I'm stuck on this question
It's solving the quadratic equation by completing the square

4x^2-x=8

Any help?
• October 14th 2009, 09:59 PM
earboth
Quote:

Originally Posted by Mist
I'm stuck on this question
It's solving the quadratic equation by completing the square

4x^2-x=8

Any help?

$x^2-\dfrac14x=2$ ......... Divide by the leading factor

$x^2-\dfrac14x+\dfrac1{64}=2 + \dfrac1{64}$ ......... take the half of the factor of x and square it. Add the square on both sides of the equation.

$\left(x-\dfrac18\right)^2= \dfrac{129}{64}$ ......... Transform the LHS into a complete square.

Calculate the square-root on both sides and solve for x.