1、(4a^2-1)(4a^2+1)(16a^4+1)
=(16a^4-1)(16a^4+1)
=256a^8-1
2﹑(x+4)(x-4)-2x(1/2x+2)=0
(x+4)(x-4)-x(x+4)=0
x^2-16-x^2-4x=0
-16-4x=0
x=-4
3﹑（1-1/2^2)（1-1/3^2)…(1-1/9^2)
=(1+1/2)(1-1/2)(1+1/3)(1-1/3)……(1+1/9)(1-1/9)
=3/2x4/3x……10/9x1/2x2/3x……8/9
=10/2x1/9
=5/9