1.20*360^2-20*335^2
=20(360^2-335^2)
=20(360+335)(360-335)
=20*695*25
=500*695
=500*(700-5)
=350000-2500
=347500
2.原式=(2-1)(2+1)(2^2+1)(2^4+1)(2^8+1)(2^16+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)
=2^32-1
3.设原式=1/2(1+1/4)(1+1/8)(1+1/16)=s
(1+1/2)s=(1+1/2)1/2(1+1/4)(1+1/8)(1+1/16)
=(1+1/2)(1-1/2)(1+1/4)(1+1/8)(1+1/16)
=(1-1/4)(1+1/4)(1+1/8)(1+1/16)
=(1-1/16)(1+1/16)(1+1/8)
=9/8 * (1-1/256)
3s/2=9/8 * (1-1/256)
s=3/4*254/256
=381/512