Question

 Aguem sabe me reponder 
x²+2x+1=81

Answer 1

x²+2x+1=81
x²+2x-80=0

Δ=b²-4ac
Δ=2²-4×1×(-80)
Δ=4+320
Δ=324

x'=-b+√Δ÷2×a
x'=-2+18÷2×1
x'=16÷2
x'=8

x"=-2-18÷2
x"=-20÷2
x"=-10

S={8,-10}

Answer 2

x²+2x+1=81
x² + 2x + 1 - 81 = 0
x² + 2x - 80 = 0

a = 1       b = + 2      c = - 80
Δ = b² - 4.a.c
Δ = (2)² - 4.(1).(-80)
Δ = 4 + 320
Δ = 324

x = - b ± √Δ
          2.a

x = - (+2) ± √324
              2.1

x = - 2 ±  18
           2

x' = - 2 + 18 =  16  =    8
           2           2

x"= - 2 - 18  =   - 20 =   - 10
          2              2

S[- 10 ; 8]