Solving for x

[Guest]

Hello,
How would you solve for x for:

a) x^3-3x^2-4x=0


and

b) 8x^3-27=0

thanks for the help, that's it for now,
Bye

 

[Unco]

You can factor out x to start a).

b) is a difference of two cubes.

 

[Guest]

How would you write out b) in factor form though? I know 2^3=8 and 3^3=27

 

[stapel]

How would you write out b) in factor form though?

Use the difference-of-cubes formula you memorized.

Eliz.

 

[Guest]

but the formula I learne didn't have x^3, but x^2..

 

[stapel]

but the formula I learne didn't have x^3, but x^2..

That would be the difference-of-squares formula. In this case, use the difference-of-cubes formula.

Eliz.