3. ( 22 + 1 ).( 24 + 1 ).( 28 + 1 )......( 264 + 1 ) + 1
= ( 22 - 1 ).( 22 + 1 ).( 24 + 1 ).( 28 + 1 )....( 264 + 1 ) + 1
= ( 24 - 1 ).( 24 + 1 ).( 28 + 1 )......( 264 + 1 ) + 1
= ( 28 + 1 ).....( 264 + 1 ) + 1
= ( 264 - 1 ).( 264 + 1 ) + 1
= 2128 - 1 + 1
= 2128
8.( 32 + 1 ).( 34 + 1 ).( 38 + 1 )....( 3128 + 1 ) + 1
= ( 32 - 1 ).( 32 + 1 ).( 34 + 1 ).( 38 + 1 )....( 3128 + 1 ) + 1
= ( 34 - 1 ).( 34 + 1 ).( 38 + 1 )....( 3128 + 1 ) + 1
= ( 38 - 1 ).( 38 + 1 )....( 3128 + 1 ) + 1
= ( 316 - 1 )......( 3128 + 1 ) + 1
= ( 3128 - 1 ).( 3128 + 1 ) + 1
= 3256 - 1 + 1
= 3256
12.( 52 + 1 ).( 54 + 1 ).( 58 + 1 ).( 516 + 1 )
Nhân cả 2 vế với 2
2 = 24.( 52 + 1 ).( 54 + 1 ).( 58 + 1 ).( 516 + 1 )
2 = ( 52 - 1 ).( 54 + 1 ).( 58 + 1 ).( 516 + 1 )
2 = ( 58 - 1 ).( 58 + 1 ).( 516 + 1 )
2 = ( 516 - 1 ).( 516 + 1 )
2 = 532 - 1
= \(\frac{5^{32}-1}{2}\)