a) We are given that f(x) = x^3 - 10x^2 + 19x + 30 and x - 6 is a factor of f(x). Using long division or synthetic division, we can divide f(x) by x - 6 to get the other factor(s):
6 │ x^3 - 10x^2 + 19x + 30
x^3 - 6x^2
-------------
-4x^2 + 19x
-(-4x^2 + 24x)
---------------
5x + 30
5x - 30
-------
0
Therefore, we can write:
f(x) = (x - 6)(x^2 - 4x + 5)
The quadratic factor x^2 - 4x + 5 cannot be factored further using real numbers.
b) We are given that f(x) = x^3 + 6x^2 + 5x - 12 and x + 4 is a factor of f(x). Using long division or synthetic division, we can divide f(x) by x + 4 to get the other factor(s):
-4 │ x^3 + 6x^2 + 5x - 12
-x^3 - 4x^2
--------------
2x^2 + 5x
2x^2 + 8x
------------
-3x - 12
-3x - 12
--------
0
Therefore, we can write:
f(x) = (x + 4)(x^2 + 2x - 3)
The quadratic factor x^2 + 2x - 3 can be factored further using the product-sum method:
x^2 + 2x - 3 = (x + 3)(x - 1)
Therefore, we have:
f(x) = (x + 4)(x + 3)(x - 1)