(a-2分之1b)〔(a+2分之1b)的2次方-(a-2分之1b)的2次方〕-2b(a的2次方-1) 把a=2b=1代入
=(1-1/4)[(1+1/4)^2-(1-1/4)^2]-2*(1/2)*(1-1)
=3/4*[(5/4)^2-(3/4)^2]
=3/4*(25/16-9/16)
=3/4*1
=3/4
(a-2分之1b)〔(a+2分之1b)的2次方-(a-2分之1b)的2次方〕-2b(a的2次方-1) 把a=2b=1代入
=(1-1/4)[(1+1/4)^2-(1-1/4)^2]-2*(1/2)*(1-1)
=3/4*[(5/4)^2-(3/4)^2]
=3/4*(25/16-9/16)
=3/4*1
=3/4