Explain why for any constant a, if y = a^x then dy/dx = a^x(ln(a))

So let's start with taking the natural log on both sides of y=ax, giving us ln(y) = ln(ax). Using the laws of logarithms we can write this as ln(y) = xln(a).Next, we differentiate both sides with respect to x, giving d/dx(ln(y)) = d/dx(xln(a)). As the term on the left hand side does not include any x terms we use the chain rule in order to differentiate with respect to y, dy/dx(d/dy(ln(y)) = d/dx(xln(a)) and then carry out the differentiation. We are then left with dy/dx(1/y) = ln(a), and, using some manipulation we find dy/dx = yln(a), and the original substitution leaves us with exactly what we're looking for y = ax(ln(a)).

JM
Answered by James M. Maths tutor

11502 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

A car is accelerating at 2 ms^-2 along a horizontal road. It passes a point A with a velocity of 10 ms^-1 and later a point B, where AB = 50m. FInd the velocity of the car as it passes through B.


Differentiate the function y=(6x-1)^7


Using the equation cos(a+b) = cos(a)cos(b) - sin(a)sin(b) or otherwise, show that cos(2x) = 2cos^2(x) - 1.


A curve with equation y = f(x) passes through the point (4,25). Given that f'(x) = (3/8)*x^2 - 10x^(-1/2) + 1, find f(x).


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning