Question

-3$x^{2}$-4x+15=0

Answer 1

$Resolu\c{c}\~ao\to \left\{\begin{array}{ccc}-3x^2-4x+15=0\\\\\Delta = b^2-4ac = 16+180 =196\\\\x = \frac{-b\pm \sqrt{\Delta} }{2a} = \frac{4\pm14}{-6} \left \{ {{x'=-( \frac{4+14}{6}) = -3 } \atop {x''=-( \frac{4-14}{6}) = - \frac{-10}{6} = \frac{5}{3} }}\\\\\boxed{S=\{-3, \frac{5}{3}\}} \right. \end{array}\right$

Espero ter ajudado. :))