(1\5)^х-1 + (1\5)^x+1<= 26

Question

(1\5)^х-1 + (1\5)^x+1<= 26

Answer 1

(1/5)ˣ⁻¹+(1/5)ˣ⁺¹≤26
5*(1/5)ˣ+(1/5)ˣ/5≤26    |×5
25*(1/5)ˣ+(1/5)ˣ≤26*5
26*(1/5)ˣ≤26*5   |÷26
(1/5)ˣ≤5
(1/5)ˣ≤(1/5)⁻¹
x≥-1
Ответ: x∈[-1;+∞).