Factorise Please

[dantheman1001]

Can someone help me factorise this please and show me how its done

3x^2 - 11x + 6

Thanks Dan

[rcd111]

-b +/- (b^2 - 4ac)^1/2
2a

a=3
b=-11
c=6

[zaza]

Welcome to the Forums :wave:



That is not factorising. That is solving, assuming that the above is equal to 0.


Factorising essentially means writing your equation in the form:

(ax + b)(cx + d)

To expand these brackets, you would simply multiply each term in one bracket by each term in the other and add them all together:

acx^2 + adx + bcx + bd


Now you can compare the powers of x, as these have to be the same for your equation:


ac = 3
ad + bc = -11
bd = 6


A useful starting point is the ac = 3 - there is only one way of multiplying two numbers to get 3 and that is if one of them is 3 and the other is 1. You can choose which.
Then think about how you'd make bd = 6, and fill in all the numbers to the middle equation and see if you get -11. (Or solve the lower two equations simultaneously if you know how).

You'll find there is a solution...


zaza