1. basic help

how to set 2x2-4x-1 eqaul to 0? do you have to factor it first or does it matter?

2. Re: basic help

Originally Posted by pnfuller
how to set 2x2-4x-1 eqaul to 0? do you have to factor it first or does it matter?
$\displaystyle b^2-4ac$ is not a perfect square, so the expression will not factor over the rationals ... you'll have to complete the square or use the quadratic formula.

3. Re: basic help

do i need the whole quadratic formula or the just b^2-4ac part you mentioned?
Originally Posted by skeeter
$\displaystyle b^2-4ac$ is not a perfect square, so the expression will not factor over the rationals ... you'll have to complete the square or use the quadratic formula.

4. Re: basic help

$\displaystyle b^2-4ac$ is part of the quadratic formula ... and yes, you need the whole formula to solve for x.

5. Re: basic help

would the answers be 2.225 and -.225

6. Re: basic help

Originally Posted by pnfuller
would the answers be 2.225 and -.225
In fact they are. But all things considered I would suspect your instructor would prefer
$\displaystyle x = \frac{2 \pm \sqrt{6}}{2}$

-Dan