I need help with these problems

Which three lengths could be the lengths of the sides of a triangle? 21 cm, 7 cm, 7 cm 9 cm, 15 cm, 22 cm 13 cm, 5 cm, 18 cm 8 cm, 23 cm, 11 cm

Find the roots of the polynomial function f(x) = x^3 + 2x^2 + x

Question 3 (essay worth 10 points) (03.06 mc) part a: max rented a motorbike at $465 for 5 days. if he rents the same motorbike for a week, he has to pay a total rent of $625. write an equation in the standard form to represent the total rent (y) that max has to pay for renting the motorbike for x days. (4 points) part b: write the equation obtained in part a using function notation. (2 points) part c: describe the steps to graph the equation obtained above on the coordinate axes. mention the labels on the axes and the intervals. (4 points)