Question 189584: Can you please help me solve this? I'm supposed to solve for all roots but I'm not sure how. Found 2 solutions by jim_thompson5910, Edwin McCravy:Answer by jim_thompson5910(35256) (Show Source):
You must learn the principle of factoring the sum and difference of
two cubes:
factors as
and
factors as
------------------------------
Your problem is the first case as it has a + sign between
the two terms:
Notice that can be written as
Notice that can be written as
So we write it as
So and
and since
factors as
we factor the left side of
as
Simplifying inside the second parentheses:
So we use the zero factor property:
,
Solving the first,
So one root is
Solving the second:
That doesn't factor so we resort to the
quadratic formula:
where , ,
Make two fractions on the right
Reduce the fractions by dividing top and
bottom by 2:
So the other two roots are
and
Edwin