posted by Rory on .
I thought with this sort of problem you are supposed to multipy 40 by 2 and get 80 and then come up with two factors that equal 13. If this doesn't work, you are supposed to factor out a number/variable.
Since neither of these methods work, is this problem unable to be factored, or am I mistaken?
Thanks in advance.
i thought it would be 15x3+40. I am not sure though
I don't think it can be factored. The factors of 40 are
and none of those number will work.
a x^2 + bx + c
calculate the discriminant:
b^2 - 4 a c.
If it is negative it cannot be factored.
In this case it is -151. The factorization involves the square root of the discriminant. If it isn't rational you won't be able to find the factorization by inspection easily either.