Linear relation questions(someone please help I will give brainliest please)

Which of the following contains a variable?

In which direction does the left side of the graph of this function point? f(x) = 3x3 - x2 + 4x - 2

Adriana had a garden where he measured the height of a corn plant. what. on the first day,it was 145 cm tall.after 2 weeks is grew by 23 cm.what is the height of the corn plant