Given:
The expression is
[tex]9x^3-39x^2-30x[/tex]
To find:
The factors by grouping method.
Solution:
We have,
[tex]9x^3-39x^2-30x[/tex]
Taking out common factors, we get
[tex]=x(9x^2-39x-30)[/tex]
Splitting the middle term, we get
[tex]=x(9x^2-45x+6x-30)[/tex]
By grouping method, we get
[tex]=x(9x(x-5)+6(x-5))[/tex]
[tex]=x(x-5)(9x+6)[/tex]
Therefore, the factor form of given expression is x(x-5)(9x+6).