:(1)1001^2-999^2
=(1001+999)(1001-999)
=2000*2
=4000
(2)1.33^2*4-1.22^2*9
=(1.33*2)^2-(1.22*3)^2
=(1.33*2+1.22*3)(1.33*2-1.22*3)
=-6.32