Reducing quadratic questions (1 Viewer)

[BlueGas]

I just wanna know what happened in the red box, where id the 3bu come from how did - u come too?

 

[davidgoes4wce]

When simplifying a quadratic with in the form ax^2+bx+c=0, if the leading term 'a' has a number other than 1, you must split the middle term up when factorising.

 

[InteGrand]

I just wanna know what happened in the red box, where id the 3bu come from how did - u come too?

 

[davidgoes4wce]

How do we obtain 36 and -1?

We obtain them because the product term is -36 (first term multiplied by the last term = a x c)

We obtain the sum term of 35 (the middle coefficient= b)

Think of two factors that give you a product of -36 and a sum of 35, in this case the only possible numbers are: 36 and -1.

 

[davidgoes4wce]

You could technically factorise is at:

4u^2+36u-1u-9=0

or

4u^2-1u+36u-9=0

 

[DatAtarLyfe]

Its just another way of factorising quadratics by splitting the middle term and then factorising in groups. Just factorise the quadratic however you usually do it and you should get the same answer

 

[InteGrand]

 

[BlueGas]

Yeah it was lol.

 

[BlueGas]

So how do I get the line before "either"? As in how did they get (4u-1)(u+9)?

 

[InteGrand]

So how do I get the line before "either"? As in how did they get (4u-1)(u+9)?