<p>Could anyone tell me how to factor a quadratic when the coefficient of the squared term is not 1?
eg. 2x^2 + x - 3</p>
<p>I knew how to do this, but it's been really long since I ever did this. I just got an MC question wrong because I didn't know how to find zeros for these kinds of quadratics.</p>
<p>The quadratic equation I had to factor on the MC section was 15x^4 - 12x^2 - 3.</p>
<p>Sorry for asking such a basic question. :o</p>
<p>Thanks.</p>
<p>Let's see...</p>
<p>Since there is only one possible way to get 2x^2 (2x and x)...it shouldn't be too bad.</p>
<p>start off with...
(2x ...)(x ...)</p>
<p>since you have a -3, it's going to be either:
(2x+ ...)(x-...)
(2x- ...)(x+ ...)</p>
<p>get some factors of -3...there's (-3 and 1, 3 and -1)
now try them
(2x-3)(x+1) = 2x^2 -3x + 2x - 3...not quite it
(2x+3)(x-1) = 2x^2 +3x - 2x - 3 = 2x^2 + x - 3
and BAM....you got it.</p>
<p>15x^4 - 12x^2 - 3
3(5x^4 - 4^2 - 1).....factor out a 3
3(5x^2 + 1)(x^2 - 1)...and BAM you got it</p>
<p>you have a nice coefficient of 5...which can only be factored as 5 and 1.</p>
<p>Or...you can always do quadratic formula =)</p>
<p>^^ I was just going to say that.</p>
<p>or...have a ti-89 and zeros(2x^2+x-3,x)</p>
<p>:D</p>