How do you solve -4x^2 + 5x + 6 = 0 ?

1 Answer
Mar 18, 2016

x = 2 and x = -3/4

Explanation:

Use the improved quadratic formula (Google, Yahoo Search)
$D = {d}^{2} = {b}^{2} - 4 a c = 25 + 96 = 121$ --> $d = \pm 11$
$x = - \frac{b}{2 a} \pm \frac{d}{2 a} = - \frac{5}{-} 8 \pm \frac{11}{-} 8 = \frac{5}{8} \pm \frac{11}{8}$
$x = \frac{16}{8} = 2$ and
$x = - \frac{6}{8} = - \frac{3}{4}$

NOTE. This improved formula is easier to remember and to proceed than the classical formula.