factorising?

hi,

im trying to find the x and y values for the following equation: y = x(x^2 - 4)

when x = 0 y= -4
but not sure what to do when y = 0
thanks

Reply 1

Hrov

2

i think that you have to either make the part in the braket =0. Or the actual x value being timesd by the bracket.

e.g. 0(0^2 -4)

or 2(2^2 - 4)

answer = 2 or 0

Reply 2

dream123

OP

2

Hrov

i think that you have to either make the part in the braket =0. Or the actual x value being timesd by the bracket.

e.g. 0(0^2 -4)

or 2(2^2 - 4)

answer = 2 or 0

how did you come to do this? 2(2^2 - 4) why did you choose to sub x=2 ?

Reply 3

Hrov

2

when y=0 you want the equation to be equal to 0
so if the part in the bracket is equal to 0, ie 2^2 -4 what ever this is timesd by outside of the bracket (2) the equation will still equal 0.

i.e. look in your brackets and make = to 0.
make your x value equal to what is being take off of it. so in this case what squared minus 4 = 0. answer being 2

or -2

OP

Hrov

when y=0 you want the equation to be equal to 0
so if the part in the bracket is equal to 0, ie 2^2 -4 what ever this is timesd by outside of the bracket (2) the equation will still equal 0.

i.e. look in your brackets and make = to 0.
make your x value equal to what is being take off of it. so in this case what squared minus 4 = 0. answer being 2

i get it now
thnks

Reply 6

Hrov

2

like mf2004 says, dont forget the -2

factorising?

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