Use a graphic calculator to determine the intervals on which (x)=2x^3-3x-1 is increasing or decreasing. Please help me I don't understand this at all because when I graph it I get 8.5 but the real answer is 0.7

Answer pls man im trying to get out of summer school

Need so much on this one how many yards?

The salesperson earns a 5% commission on the first $5,000 she has in sales. the salesperson earns a 7.5% commission on the amount of her sales that are greater than $5,000. this month the sales person had $8,000 in sales. what amount of commission, in dollars, did she earn?