Please help. I don't understand

9514 1404 393

  8m³ -4m² +3m

Step-by-step explanation:

The perimeter of a triangle is the sum of the lengths of its three sides. Here, you're given the perimeter and two of the sides. The third side will be the length that makes up the difference.

  P = side 1 + side 2 + side 3

  18m³ +2m² -m = (5m³ +3m² -2m) +(5m³ +3m² -2m) + side 3

  18m³ +2m² -m = (10m³ +6m² -4m) + side 3 . . . . . collect terms

  18m³ +2m² -m - (10m³ +6m² -4m) = side 3 . . . . . subtract (10m³ +6m² -4m)

  m³(18 -10) +m²(2 -6) +m(-1 +4) = side 3 . . . . . . . . . group like terms

  8m³ -4m² +3m = side 3

Vertex is (-2,-3) and it's a minimum.