直接代入嘛2A -B = 2(4a^2 +5b) -(-3a^2 -2b) = 8a^2+10b +3a^2+2b = 11a^2 +12b答案是A
2A-B=2(4a²+5b)—(-3a²-2b) =8a²+10b+3a²+2b =11²a+12b选A
A