Find the exact solution to: ln(x) + ln(7) = ln(21)

Log rules:

log(a) + log(b) = log(ab)

so, in this case, we must find x such that 7x = 21

thus x = 3

similarly, log(a) - log(b) = log(a/b)

rearranging the original equation we get:

ln(x) = ln(21) - ln(7)

so x = 21/7 = 3

BP
Answered by Bryan P. Maths tutor

6495 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

How do you find the maximum/minimum value of an equation?


What are partial fractions for and how do I find them?


A curve C has equation y = (2 - x)(1 + x) + 3 . A line passes through the point (2, 3) and the point on C with x-coordinate 2 + h . Find the gradient of the line, giving your answer in its simplest form.


How does one find the equation of a line passing through 2 points of a graph?


We're here to help

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

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences