How do I solve a quadratic equation?

The best way to solve a quadratic function is to put brackets into the equation.

Start with an example

Find x when y=0 for the function 

y=x*2 + 5x + 6

As y=0 make the whole equation= 0:

x*2 + 5x + 6=0

Try and put this into brackets:

(x+a)(x+b)=0 (as all the values are positive, we know that there are going to be no negative signs in the brackets).

Now we just need to find values for a and b that multiply out to give us the equation we need.

Try a=6 and b=1:

This gives us the 6 at the end but when multiplied out gives us 7x- which is too much.

Now try a=2 and b=3 and multply out:

We get 0=x2+ 2x + 3x + 6= x2 + 5x + 6 ... which is what we want!

So we get (x+2)(x+3)=0

For it to equal 0 either:

x+2=0 so x=-2 or

x+3=0 so x=-3

so x=-2, -3

RB
Answered by Rosiered B. Maths tutor

3782 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

You and your brother have your pocket money split in the ratio 2:7. If your brother receives £42, how much do you receive?


A cylinder has a radius of 4 cm and volume of 800 cm3. A similar cylinder with the same height has a volume of 200 cm3. Find the radius of the smaller cylinder.


Solve the simultaneous equations: 2x + y = 12; x - y = 6


Solve the simultaneous equations 'x-2y=3' and 'x^2+2y^2=27'


We're here to help

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

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences