Question

Resolva 2x^2 - 5x - 12 >= 0
Muito obrigada!

Answer 1

$2x^2-5x-12=0\\ a=2\\ b=(-5)\\ c=(-12)$

$\Delta=b^2-4\cdot a\cdot b\\ \Delta=(-5)^2-4\cdot2\cdot(-12)\\ \Delta=25+40\\\Delta=65$

$\dfrac{-b\pm\sqrt{\Delta}}{2\cdot a}=\\ \dfrac{-(-5)\pm\sqrt{\Delta}}{2\cdot2}=\\ \dfrac{5\pm\sqrt{25+40}}{4}=\\ \dfrac{5\pm\sqrt{65}}{4}$

$x'=\dfrac{5+\sqrt{65}}{4}$

$x''=\dfrac{5-\sqrt{65}}{4}$