(iii) (9+7x)1/2−(16+3x)1/44+5x≈14−17384x\dfrac{(9+7x)^{1/2} - (16+3x)^{1/4}}{4+5x} \approx \dfrac{1}{4} - \dfrac{17}{384}x4+5x(9+7x)1/2−(16+3x)1/4≈41−38417x