Quadratic Formula

Question

Select the approximate values of x that are solutions to f(x)=0, where f(x)=-9x^2+5x+7

 

A. (1.20,-0.65)

B. (-9,5)

C. (-0.56,-0.78)

D. (-1.29,0.71)

Answer 1

I find that having the (-) on the x² can sometimes make the quadratic formula confusing, as having the correct sign on the a,b, and c values is critical to get the correct answer. Multiply the whole equation by -1 and give the quadratic equation another shot!

 

The discriminant: b² - 4*a*c is also a very helpful tool for solving polynomials.

 

Hope this helps!