Answer:
Part A: 5x² + 7x - 4
Part B: 5x³ - x² - 8x + 1
Part C: Yes.
Step-by-step explanation:
Part A: The length of two sides of a triangle are given by
Side 1: 3x² - 2x - 1
Side 2: 9x + 2x² - 3
Now, the total length of the two sides, 1 and 2, of the triangle will be
= (3x² - 2x - 1) + (9x + 2x² - 3)
= 5x² + 7x - 4 (Answer)
Part B: If the length of the third side is y and the perimeter of the triangle is (5x³ + 4x² - x - 3), then
y = (5x³ + 4x² - x - 3) - (5x² + 7x - 4) = 5x³ - x² - 8x + 1 (Answer)
Part C: The answers in the part A and part B are closed under addition and subtraction. (Answer)