The luminous intensity L L\,L of a specific lamp is measured as a function of the distance d d\,d from the filament. Under certain conditions, the intensity is modeled by
L(d)=(27+4d5)−23 L(d) = \left( 27 + \frac{4d}{5} \right)^{-\frac{2}{3}} L(d)=(27+54d)−32Determine the range of values of d d\,d for which the binomial expansion of L(d)L(d)L(d) in ascending powers of d d\,d is valid.
308 exam-style questions on OCR A Level Maths 1.4 Sequences and Series, covering 1.4.1 Binomial expansion for positive integer n, 1.4.2 Link to binomial probabilities, 1.4.3 Binomial expansion for rational n (A-level only), 1.4.4 Validity of the expansion (A-level only), 1.4.5 Sequences (A-level only), 1.4.6 Increasing, decreasing and periodic sequences (A-level only), 1.4.7 Sigma notation (A-level only), 1.4.8 Arithmetic sequences and series (A-level only), 1.4.9 Geometric sequences and series (A-level only), 1.4.10 Sum to infinity of a geometric series (A-level only), and 1.4.11 Modelling with sequences and series (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.