1.9.10 Differentiate e^kx, a^kx and ln x (A-level only)

A physicist models the intensity of radiation, $I$ , at a distance $x\,$ metres from a point source using the equation

\frac{25}{x^3} + 0.4^x, \quad x \ge 1

Find an expression for the rate of change of radiation intensity with respect to distance, $dIdx\dfrac{dI}{dx}$ .

[2]

A physicist models the intensity of radiation, $I$ , at a distance $x\,$ metres from a point source using the equation

\frac{25}{x^3} + 0.4^x, \quad x \ge 1

Find an expression for the rate of change of radiation intensity with respect to distance, $dIdx\dfrac{dI}{dx}$ .

[2]

1.9.10 Differentiate e^kx, a^kx and ln x (A-level only) Questions