y=2^x-2^-x=e^(xln2)-1/e^(xln2)y'=ln2e^(xln2)+1/[e^(xln2)]^2*ln2e^(xln2) =ln2*2^x+ln2*2^x/[2^x]^2 =ln2*2^x+ln2/2^x【公式更快y=a^xy'=a^xlna
