2的a次幂 +3a=3的b次幂 +2b①设m=a-b,则a=b+m,①左-右=2^(b+m)-2^b+3m=2^b*(2^m-1)+3m,记为f(m),f'(m)=2^b*2^m*ln2+3>0,所以f(m)是增函数，其零点唯一：f(0)=0.所以由①得a-b=0,即a=b.
