總複習恆等式

(3x^2+2y)(-3x^2c+2y)<---write wrong?
(4m+7)^2
=16m^2+56m+49
(6x-5y)^2
=36x^2-60xy+25y
(9-pq)^2
=81-18pq+p^2*q^2
(3x+1/2)^2
=9x^2+3x+0.25 (0.25=1/4)
求下列各數的值
22.5^2-7.5^2
=(22.5-7.5)(22.5+7.5)
=15*30
=450
1.003^2
=(1+0.003)^2
=1+2.006+9.0 × 10^-6
=3.006009
999^2
=(1000-1)^2
=1000000-2002+1
=997999