Question

Quem eo vigesimo termo dessa P.A?(-8,-3,2,7,....)

Answer 1

a₁ = -8
a₂ = -3
a₃ = 2
n = 20
r = -3 - (-8) = 5
          a₂₀ = a₁ + (n - 1) * r 
          a₂₀ = -8 + (20 - 1) * 5
          a₂₀ = -8 + 19 * 5
          a₂₀ = -8 + 95
          a₂₀ = 87

Espero ter ajudado. Valeu!

Answer 2

$\begin{array}{l}\sf a_n=a_1+(n-1)\cdot r\\\\\sf a_{20}=-8+(20-1)\cdot5\\\\\sf a_{20}=-8+19\cdot5\\\\\sf a_{20}=-8+95\\\\\boxed{\boxed{\sf a_{20}= 87}} \end{array}$