2x^2+x-1=0

Question

Solve the quadratic by the quadratic formula

Answer 1

2x² + x - 1 = 0

 

For a general quadratic equation of the form ax²+bx+c=0, the quadratic formula is:

 

x = [-b±√(b²-4ac)] / 2a

 

In this case, a=2, b=1, c= -1.  Plugging them in:

 

x = [-2±√(1²-4(2)(-1))] / 2(2)

x = [-2±√(1+8)] / 4

x = [-2±√9] / 4

x = -1/2 ± 3/4

 

x = 1/4, -5/4