Đặt \(A=3\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)
Ta có:
\(3=2^2-1\)
Do đó:
\(A=\left(2^2-1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^{16}+1\right)\)
Liên tiếp áp dụng hằng đẳng thức \(a^2-b^2=\left(a-b\right)\left(a+b\right)\)ta được:
\(A=\left(2^4-1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)
\(A=\left(2^8-1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)
\(A=\left(2^{16}-1\right)\left(2^{16}+1\right)=2^{32}-1\)
=(2^2-1)(2^2+1)(2^4+1)(2^8+1)(2^16+1)
=(2^4-1)(2^4+1)(2^8+1)(2^16+1)
=(2^8-1)(2^8+1)(2^16+1)
=(2^16-1)(2^16+1)
=2^32
kb và k cho mk nhé!!!!!!!!!! ^_^ ^_^
3(22+1)(24+1)(28+1)(216+1)
=\(3.\frac{1}{2^2-1}.\left(2^2-1\right)\left(2^2+1\right)...\left(2^{16}+1\right)\)
=\(3.\frac{1}{3}.\left(2^4-1\right)\left(2^4+1\right)...\left(2^{16}+1\right)\)
=\(\left(2^8-1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)
=\(\left(2^{16}-1\right)\left(2^{16}+1\right)\)
=\(2^{32}-1\)
3(22+1)(24+1)(28+1)(216+1)
=(22-1)(22+1)(24+1)(28+1)(216+1) tách 3 thành 22-1
=(24-1)(24+1)(28+1)(216+1)
=(28-1)(28+1)(216+1)
=(216-1)(216+1)
=232-1
Bài này lớp 9 rồi ko phải lớp 7