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.

LS
Answered by Lior S. Maths tutor

6990 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

How do I expand the following equation (x+4)(x+2)


Solve the quadratic equation x^2 + x - 20 = 0


There are 2 banks, Bank A and Bank B. Bank A provides compound interest of 1.3%. Bank B provides interest of 3.5% for the first year and then 0.7% for each extra year. James wants to invest £250. Which bank provides the most interest after 4 years?


The point P has coordinates (3, 4) The point Q has coordinates (a, b) A line perpendicular to PQ is given by the equation 3x + 2y = 7 Find an expression for b in terms of a.


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