Question

23 PONTOS
determine as raízes da equação
$x {}^{2} + 4x - 21 = 0$

Answer 1

x²+4x-21=0

∆= 4²- 4.1.(-21)

∆= 16 +84

∆= 100

x= -4±√100/2.1

x= -4±10/2

x1= -4+10/2= 6/2=3

x2= -4-10/2=-14/2=-7

S={3,-7}