part (iv) h is small

k part (i) find integral of (1)/(4x^2+9)^0.5 dx between limits 0 and 2 DONE

(ii) given f(x)=arsinh(4/3+x) find f'(x) f''(x) bladeblah..

(iii) find maclaurin series for arsinh(4/3+x) as far as x^2

(iv) hence show that, when h is small integral of xarsinh(4/3+x)dx

roughly = (2/3)(h)^3

i got part (iii) as; ln3 + (4+3x)/5 -(54x^2 +144x +96)/125 +....

presuming this is wright in (iv) i get some utter rubbish -ve no. i screwed it up in rage! grr ???