Find the roots of the formula x^2 + 4x + 3 by factorising.

x2 + 4x + 3 is a quadratic equation. We're looking for a pair of numbers that add to make 4, and multiply together to make 3. Students should be encouraged to try options (e.g. 2 and 2).
The pair we need is 3 and 1. Because there is no coefficient on the x2 term, we don't have to worry about what order they will go in, we'll just have two x + n brackets. So we get: (x + 3)(x + 1).
Then we set (x + 3)(x + 1) = 0 and solve for the two possible values of x (-1 and -3). Students should explain two important learnings points: 1. that setting the formula to zero is asking us the question "what values does this line take when it cuts the x axis?" and 2. that we can use the (x + m)(x + n) = 0 pattern to find x because at any time, at least one of the brackets must equal 0.

Answered by Joseph B. Maths tutor

2585 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

The equation of a curve is y = (x + 3)^2 + 5. Find the coordinates of the turning point.


25* 3/2


Factorise this formula completely 2kx + 6ky + 4kz


Express the number 252 in terms of its prime factors


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