How do you factorise the following quadratic: x^2 - 5*x - 14?

An example of an application of factorising quadratics is to find the unknown in the equation, x. Factorising means writing the above equation in the form (x+a)(x+b)=0 Using FOIL (First, Outer, Inner, Last) to expand the brackets we get the equation: x^2+(a+b)x+ab=0 which we can see is in the same format as the expression given. Factorising is just the reverse of expanding the brackets. So we need to find the variables a and b. As we can see from our expanded standard equation the coefficient of the second term is a+b and the coefficient of the last term is a*b. So we need to find two numbers that add together to make 5 and multiply to make negative 14. Lets start with the factors of -14 which are: -1 and 14 -2 and 7 1 and -14 2 and -7 2 and -7 added together make -5 so these are a and b. So we write them into the equation: (x+2)(x-7)=0. And this is our answer. 

EP
Answered by Emma P. Maths tutor

3594 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

The probability that it rains on a given day is 0.15. The probability that a football match is cancelled when it rains is 0.65. If it doesn't rain, the probability that the match is not cancelled is 0.95. What is the chance that the match is cancelled?


Find the roots of the following equation x^2 + 6x + 5 = 0


Solve the linear equation 4x+5=-6x+15


x = 0.436363636... . Prove algebraically that x can be written as 24/55.


We're here to help

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

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning