What is (5+3i)*(3+5i)

The idea here is to explain to the student that i^2=-1, and to expand and simplify the brackets in question just like they would with simple algebra. Therefore:
(5+3i)*(3+5i)=15+25i+9i+15i^2=15+34i-15=34i
Students can often multiply out the brackets correctly, but then they are not sure what to do with term involving "i^2". Confusion is even bigger if there are minus signs floating around.

Answered by Sebastian K. Maths tutor

2800 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

How to do the chain rule.


Find the general solution to the differential equation '' (x^2 + 3x - 1) dy/dx = (2x + 3)y ''


Find the value of 4!/0!


What is the magnitude and direction of the resultant force of 3N horizontal and 5N vertical?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences