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

2632 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

There are 30 yellow sweets and 10 black sweets in a bag. Two sweets are taken out at random without replacement. Work out the probability that the two sweets are the same colour.


Expand the brackets: (2x + 4)(x + 3)


There are n sweets in a bag. 6 are orange. A random sweet gets eaten, and then a second one. The probability that both sweets are orange is 1/3. Find n.


How do I find the equation of a line that is perpendicular to another line?


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