Question

b(ao quadrado) -4ac, para a=1, b=2 e c= -15

Answer 1

$\Delta~=b^{2}-4ac \\ \Delta~=2^{2}-4.1.(-15) \\ \Delta~=4+60 \\ \Delta~=64 \\ \\ x=\frac{-b+/- \sqrt{\Delta~}}{2a} \\ x= \frac{-2+/- \sqrt{64}}{2.1} \\ x= \frac{-2+/-8}{2} \\ \\ x'= \frac{-2+8}{2} \\ x'=3 \\ \\ x''= \frac{-2-8}{2} \\ x''=-5$