Evaluate (int_{1}^{2} frac{4}{x^{3}} mathrm {d} x)

(int frac{4}{x^{3}} mathrm {d} x = int 4x^{-3} mathrm {d} x)

(frac{4x^{-3 + 1}}{-2} = -2x^{-2}|_{1}^{2} = frac{-2}{x^{2}}|_{1}^{2})

= (frac{-2}{2^{2}} – frac{-2}{1^{2}} = -frac{1}{2} + 2 = 1frac{1}{2})

A cheque that is payable to whoever presents it is known as______