Question

expand y=(x-3)(x+1)(x+3)

Answer 1

have you tried to do it?

Answer 2

the answer i got is \[x ^{3}+x ^{2}-9x-9\]

Answer 3

yep, that's it. well done

Answer 4

owh okay thank you... how do i factorize it again?

Answer 5

so you want to know how to factorise a cubic?

Answer 6

yes :D

Answer 7

ok watch carefully.....

start by grouping

x^3 + x^2 - 9x -9

becomes (x^3 + x^2) and (-9x - 9)

1st group becomes x^2(x+1) and 2nd group -9(x+1)

each term has the same factor x+1 so we can combine the factors

and we get (x^2-9)(x+1)

looking at x^2-9 we need to find two roots that add up to 0 and when multiplied become -9

these are +3 and -3, so we have (x+3)(x-3)(x+1)

so there you go

Answer 8

is that clear?

Answer 9

Going through it
:) give me a min, then i'll be done

Answer 10

if we use long division or the synthetic method, it also can be solved right?

Answer 11

yes of course, but you need to firstly work out one of the roots