How do I expand (x+a)(x+b)? (plus example)

The key to understanding expanding brackets is to understand that we need to multipy EVERYTHING in the first bracket by EVERYTHING in the second bracket.

We can think of the calculation

(x+a)(x+b)

as

x(x+b) + a(x+b)

(by simply splitting up the first bracket).

Multiplying out both brackets then gives

xx + xb + ax + ab,

which is equal to 

x+ ax + bx + ab, which is our final answer.

 

 

Example: Expand (x+3)(x+4).

We can think of this as

x(x+4) + 3(x+4),

which we can see is equal to

xx + 4x + 3x + 12,

so our final answer is

x2 + 7x + 12.

JB
Answered by Jenny B. Maths tutor

15278 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

A truck is carrying 8.5 tonnes of produce. Find the amount of produce the truck is carrying in kg.


Write 16× 8^2x as a power of 2 in terms of x.


gradient and differentiation


Factorise and solve x^2 - 8x + 15 = 0


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