[23six]

Been bugging me for the last hour lol, I dont know if I'm missing anything out.

Factorise: 2x² - x - 3

After a google search I know the answer (which i wont reveal because I dont know how to spoiler) but I dont understand.

From my knowledge you times the coefficient of x² (2) by -3 = -6
Now find two numbers that:
(a) multiply to make -6 and
(b) add/subtract to make -1 (for -x ofc)

This seems impossible to me

Any help with steps would be appreciated!

[Idle]

-3 and +2?

[23six]

(Original post by Idle)
-3 and +2?

Oh yh, ****

[Sophieeexxx]

2x^2-x-3

(2x+3)(x-2) = 0

X = 2 or -1.5

I don't know if this is completely wrong but I think the first part is right, I don't know where it goes after that


This was posted from The Student Room's iPhone/iPad App

[Fragile_Illusions]

You need to get a proper calculator. You don't have to work this out in the exams.

-3 * +2 = -6
-3 + 2 = -1

[Sophieeexxx]

Ooh no wait that 2 is a one


This was posted from The Student Room's iPhone/iPad App

[23six]

How dyou factorise 2x^2 -3x +2x -3 then please?

[Sophieeexxx]

And the + and - are the other way round. Gah ignore me I made a mess haha D


This was posted from The Student Room's iPhone/iPad App

[Sophieeexxx]

(Original post by 23six)
How dyou factorise 2x^2 -3x +2x -3 then please?

It's the same
-3x +2x = -x


This was posted from The Student Room's iPhone/iPad App

[Robbie242]

(Original post by 23six)
How dyou factorise 2x^2 -3x +2x -3 then please?

2x(x+1) -3(x+1)

(2x-3) (x+1)

EDIT: Rearranged the twos and 3s together to get a common factor (x+1) then put the two numbers outside the brackets into a separate one alongside it.

[mimx]

(Original post by 23six)
How dyou factorise 2x^2 -3x +2x -3 then please?

Edit: Beat

[Robbie242]

(Original post by mimx)



Edit: Beat

Aww only by a few seconds! ^^

[23six]

Thanks guys! I see where I confused myself now. Put the +2x -3x the other way around making it all weird

[ViceVersa]

X1 = 1.5 X2 = -1

I other words: (2x-3) (x+1)