Final answer:
The perimeter of a triangle with sides 2x, 1x-4, and 3x+9 is found by adding the sides together, resulting in a formula 6x + 5.
Step-by-step explanation:
The perimeter of a triangle is the sum of the lengths of its sides. Given a triangle with sides 2x, 1x-4, and 3x+9, we can find the perimeter by adding these side lengths together:
Perimeter = 2x + (1x-4) + (3x+9).
Combining like terms gives us:
Perimeter = (2x + 1x + 3x) + (-4 + 9),
Perimeter = 6x + 5.
Without the specific value of x, we can only express the perimeter in terms of x, as 6x + 5.