Question 27450
Hint:  You can indicate x-squared by using the "caret", thus: x^2

Factor completely:
1) {{{x^2-5x-14}}}
If this trinomial expression factors, the factors will take the form: (x+m)(x+n) where: (m)*(n) = -14 and (m)+(n) = -5

Try m = -7 and n = +2

(2)(-7) = -14 and (2) + (-7) = -5

The factors are: (x-7)(x+2) Check using the FOIL method:
{{{(x-7)(x+2) = x^2+2x-7x-14}}} = {{{x^2-5x-14}}}

2) {{{3x^2-2x-8}}}
If this trinomial expression factors, the factors will take the form: (3x+m)(x+n) where: (m)*(n) = -8 and (m)+(3n) = -2

Try m = 4 and n = -2

(4)*(-2) = -8 and (4)+3(-2) = 4-6 = -2

The factors are: (3x+4)(x-2) Check using the FOIL method:
{{{(3x+4)(x-2) = 3x^2-6x+4x-8}}} = {{{3x^2-2x-8}}}

3) {{{24x^2+10x-4}}}
This one requires a little more work because of the lager number of possible factors of the coefficient of x^2 (24).
First, list the factor-pairs of 24:
1 X 24 = 24
2 X 12 = 24
3 X 8 = 24
4 X 6 = 24

The choices of factors of the constant term in the given expression are:
1 X -4 = -4
-1 X 4 = -4
2 X -2 = -4

Now you need to select a pair from the first list of factors and a pair from the second list of factors and, through an educated trial-and-error process, combine them to form the factors of the given expression.
I would try 3 and 8 from the first list and 2 and -2 from the second list. Let's see what happens:

{{{(3x+2)(8x-2) = 24x^2-6x+16x-4}}} = {{{24x^2+10x-4}}} Ok, a lucky(?) guess.