Expand (16−3x)12\displaystyle (16 - 3x)^{\frac{1}{2}}(16−3x)21 in ascending powers of x x\,x up to and including the term in x3x^3x3.
Write down the range of values of x x\,x for which the expansion is valid.
Use your expansion, with a suitable value of xxx, to find the value of 15.7 \sqrt{15.7}\,15.7 correct to 5 significant figures.