Question

Obter x, X e R de modo que o número complexo z=11+(x2-3x-4)1 seja real?

Answer 1

z=11+(x²-3x-4)i

x²-3x-4=0
∆=(-3)²-4.1.(-4)
∆=9+16
∆=25

x= -(-3)±√25/2.1
x= 3±5/2
x1= 3+5/2 = 8/2= 4
x2= 3-5/2= -2/2= -1