Maths

ThatIrishGuy

Has anyone got all the relevant formulas we have to learn that arent in the tables?

Thanks

paaula

I know the ones for algebra since i have just been revising it.
you have to know:
x^3+y^3= (x+y)(x^2-xy+y^2)
x^3-y^3= (x-y)(x^2+xy+y^)

b^2-4ac>0 two real roots
b^2-4ac=0 two equal roots
b^2-4ac<0 no real roots

α+β= -b/a (sum of two roots)
αβ= c/a (product of two roots)

how to make an equation: x^2- x(sum of roots) + (product of roots)

α^2+β^2= (α+β)^2-2(αβ)
α^3+β^3= (α+β)^3-3(αβ)(α+β)

ChemHickey

paaula wrote: »

I know the ones for algebra since i have just been revising it.
you have to know:
x^3+y^3= (x+y)(x^2-xy+y^2)
x^3-y^3= (x-y)(x^2+xy+y^)

b^2-4ac>0 two real roots
b^2-4ac=0 two equal roots
b^2-4ac<0 no real roots

α+β= -b/a (sum of two roots)
αβ= c/a (product of two roots)

how to make an equation: x^2- x(sum of roots) + (product of roots)

α^2+β^2= (α+β)^2-2(αβ)
α^3+β^3= (α+β)^3-3(αβ)(α+β)

I use the same for the alpha ^ 3 one but you can use the same one as is for x ^3 +y^3 instead of learning two different ones!

paaula

Yeah, I think you can just learn one of them. After all they would both give you the exactly same result. Personally I would learn the alpha^3+beta^3 one since they ask you to find it sometimes in exam questions. But you can just use the x^3+y^3 as well, it would just take you longer to work it out if they ask you about the alpha and beta.

ThatIrishGuy

Brilliant greatly appreciated youre a lifesaver!