Factorise x^2-x-6=0, and solve, finding the values of x

When you factorise an equation, the final form should look like this: (x+a)(a+b)=0 in order to work out the possible value(s) for x. As a result, working backwards, we expand the already factorised final form into x^2+ax+bx+ab=0. As this is a generalised form, we can use this to work out the factorised form of x^2-x-6=0. Therefore, ab has to equal -6. Consequently, ax+bx=-1x. This tells us that a+b=-1. We now have to different equations that can help us to work out what the values of a and b are, as the values of a and b need to give -6 when multiplied together, as well as give the answer of -1 when added together. Going through the possible values that a/b may have, we find that -3 and 2 work, as (-3)(2)=-6, and (-3)+(2)=-1. This, therefore, gives us the answer to the first part of the question. The factorised form of x^2-x-6=0 is (x-3)(x+2)=0. To answer the next part of the question, we use this factorised form. We know that anything multiplied by 0 gives the answer 0. Therefore, as the result of this equation is given to equal to 0, we know that either x-3, or x+2, have to give the value of 0. We can now make two separate equations, x-3=0, and x+2=0. This gives us the values of x to be 3, and -2, and hence we have solved the problem.

Answered by Lior S. Maths tutor

4596 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Show that (x+2)(x+3)(x+4) can be written in the form of ax^3+bx^2+cx+d where a, b, c and d are positive integers.


Find the values of x that satisfy the quadratic equation: x^2 + 14x + 40 = 0


For the equation x^2 - 2x - 8 = y find: (a) The roots. (b) The y-intercept. (c) The coordinate of the turning point


How do you factorise x^2 -4 = 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 2013–2024

Terms & Conditions|Privacy Policy