①
(2m+3)²
=4m²+12m+9
②
(-1.3a+2b)²
=1.69a²-5.2ab+4b²
③
(-2p-7q)²
=(2p+7q)²
=4p²+28pq+49q²
(a-3分之1b)²
=a²-2ab/3+b²/9