Question

tem mais essa -x2+5x+7=0

Answer 1

$-x^2+5x+7=0 \\ \\ \Delta=5^2-4.(-1).7 =25+28= 53\\ \\ \boxed{x=\frac{-5+-\sqrt{53}}{2.(-1)}=\frac{-5+-\sqrt{53}}{-2}}$

Answer 2

-$x^{2}$ + 5x +7 = 0
a = -1, b= 5, c= 7

delta = $b^{2}$ - 4.a.c
delta = $5^{2}$ - 4.(-1).7
delta = 25 + 28
delta = 53

x = - b +- $\sqrt{delta}$ /2.a
x = - 5 +- $\sqrt{53}$ /2.(-1)
x = - 5 +- $\sqrt{53}$ /-2

logo:
x = - 5 + $\sqrt{53}$ /-2
x = - 5 - $\sqrt{53}$ /-2

ESPERO TER AJUDADO!