a)\(4\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\)
\(=\dfrac{1}{2}.\left(3^2-1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\)
\(=\dfrac{1}{2}.\left(3^4-1\right)\left(3^4+1\right)\left(3^8+1\right)\)
\(=\dfrac{1}{2}.\left(3^8-1\right)\left(3^8+1\right)\)
\(=\dfrac{1}{2}.\left(3^{16}-1\right)\)
\(=\dfrac{1}{2}3^{16}-\dfrac{1}{2}\)
b) \(48\left(5^2+1\right)\left(5^4+1\right).....\left(5^{32}+1\right)\)
\(=2.\left(5^2-1\right)\left(5^2+1\right)\left(5^4+1\right).....\left(5^{32}+1\right)\)
\(=2.\left(5^4-1\right)\left(5^4+1\right).....\left(5^{32}+1\right)\)
\(=2.\left(5^8+1\right).....\left(5^{32}+1\right)\)
\(=2.\left(5^{32}-1\right)\)
\(=2.5^{32}-2\)
Tham khảo nhé~
