how do I solve this for x?
17x+x^2= 90

Question

how do I solve this for x?
17x+x^2= 90

accessdenied · Answer

Do you know how to solve the equation in this form:
 $ax^2 + bx + c = 0$
?

anonymous · Answer

kinda?? I really can't remember....

accessdenied · Answer

We would want to put it into that form.  There are ways we can find the solutions when all the information is on one side.  :)

So, we just have to subtract off the 90 from both sides and we should have this:
$ x^2 + 17x - 90 = 0$

anonymous · Answer

ok, then where do we go?

accessdenied · Answer

It doesn't seem factorable to me, so we have to use something else.
Do you recall the quadratic formula?
$$ \quad x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} $$
Basically, we just have to plug in $a = 1$, $b=17$, and $c = -90$ here and it should give us the solutions.  :)

anonymous · Answer

oh! the quadratic formula!:) i remember now! thanks so much for your help!!

accessdenied · Answer

You're welcome.  :)

accessdenied · Answer

I get:

-17 +- sqrt(649)
-----------------
           2

649 seems to only break into 11 and 59 as prime factorization, so nothing really comes out of the radical.

anonymous · Answer

yea i got it:)