Expert: Bobby Soltani - 2/14/2005

Question
solve the given quadratic equations by factoring

P^2-6P-27=0

Answer
Hi Jim,

We want the final form to look like this:

(p + a)(p + b) = 0
if we multiply this out, we get

p^2 + (a+b)p + a*b = 0

comparing this with our equation, we have

a+b = -6  and  a*b = -27

we can see that to get 27, we can multiply -9 times 3.  So if we let a=-9 and b=3, then both equations are satisfied.  So the result is

(p-9)(p+3) = 0

we can now easily see that the equation is zero when p=9 or when p=-3.

Let me know if you have any questions.

Bobby