Question

X (elevado) a 2 - x - 20 = 0

Answer 1

Δ= b²-4ac
Δ= (-1)² -4. 1. (-20)
Δ= 1+80
Δ= 81
Δ= 9
x= - b +ou - √Δ
            2a

x¹=  -1 +9  = 4     e x² = -5
           2

Answer 2

∆ = 1-4.1. (-20) ∆ = 1 + 80 ∆ = 81 x = -b +/- √∆ / 2.a x = -(-1) +/- √81 / 2.1 x = 1 +/- 9 / 2 x1 = 1 + 9/2 = 5 x2 = 1 - 9/2 = -4