We are given the coordinate of the 3 vertices. From these coordinates we can find the length of the sides using the distance formula and the sum of all the sides will be equal to the perimeter of the triangle.
Side PQ =
Side QR =
Side RP =
So, the perimeter of the triangle will be 8 + 4.5 + 7.2 = 19.7
You probably misplaced the digits in option A. The correct answer is 19.7 units.
The correct answer is: if is a root of , then is also a root of .
In fact, every polynomial has real and/or complex solutions. If all solutions are real, we're good. But if not all of them are real, then the complex ones come in couple of conjugate solutions. Since and are conjugate complex numbers, if one of them is a solution, the other must be as well.