How do you factor and solve 9x^2 + 7x - 56 = 09x2+7x56=0?

1 Answer
Jul 4, 2016

(-7 +- sqrt2065)/18

Explanation:

f(x) = 9x^2 + 7x - 56 = 0f(x)=9x2+7x56=0
D = d^2 = b^2 - 4ac = 49 + 2016 = 2065D=d2=b24ac=49+2016=2065
Since D is not a perfect square, this function can't be factored.
Solve f(x) = 0 by the improved quadratic formula.
D = 2065 D=2065 --> d = +- sqrt(2065)d=±2065
There are 2 real roots:
x = -b/(2a) +- d/(2a) = - 7/18 +- sqrt(2065)/18 = (-7 +- sqrt(2065))/18x=b2a±d2a=718±206518=7±206518