Use the quadratic formula to solve this equation to 3sf: 5x^2-2x-11=0

X=1/5+2/5√14 or 1/5 + - 2/5√14

The quadratic formula is the result of completing the square for ax^2+bx+c=0 and it is:

x = (-b±√ (b^2-4ac)) / (2a) in this case:

x = (2±√ (4-4 (5) (-11)) / (2 (5))

x = (2±√224) / 10

x = (2±4√14) / 10

x = (1±2√14) / 5

x≈ (-1.30, 1.70) (to three significant figures)