\(25A=5^4+5^6+...+5^{102}\)
\(\Rightarrow25A-A=24A=5^{102}-5^2\)
\(A=\frac{5^2\left(5^{100}-1\right)}{24}\)
A = 52 + 54 + 56 + ... + 5100
52.A = 54 + 56 + 58 + ... + 5102
52.A - A = (54 + 56 + 58 + ...+ 5102) - (52 + 54 + 56 + ... +5100)
25A - A = 5102 - 52
24A = 5102 - 52
A = 5102 - 52/24
Ủng hộ mk nha ♡_♡