The Student Room Group
take out a factor of x for a start...

+ you can divide through by 4.
Reply 2
20x^3-4x=0
4x * (5x^2-1) = 0
x * (5x^2-1) = 0
Reply 3
20x^3 - 4x = 0
5x^3 - x = 0
x(5x^2 - 1) = 0
4x(5x^2 -1) = 0
solve 5x^2 -1 = 0

Doesn't matter if you simply it first, the end result is still the same, the factorized form that is.

x = 0 and x = root(1/5)
boromir9111
x = 0 and x = root(1/5)

And...
-root(1/5)
Yep. :smile:
:smile:
Hope that helps you OP in understanding factorizing.
Reply 10
generalebriety
I hope this is a joke. A correct factorisation is 4x(5x^2 - 1), but it factorises further. (Difference of two squares...?)

unless Im missing something why is that the difference of 2 squares?5 surely is not a square no..
rbnphlp
unless Im missing something why is that the difference of 2 squares?5 surely is not a square no..


Well you can still factorise it (5x+1)(5x1)(\sqrt5x+1)(\sqrt5x-1) which is using the difference of 2 squares method.
rbnphlp
unless Im missing something why is that the difference of 2 squares?5 surely is not a square no..

5 is the square of 5\sqrt{5}.
Reply 13
*facepalm*

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