please answer all of them, it's urgent!

4. The position function of an object is given by s(1) = 2 - 121 + 30t + 8, where time, t, is in seconds and distance, s, is in metres. What is the object's acceleration at / = 1? (2K, 2A) 5. The demand function for a product is given by p(x) = 10 000-0.05x, where x is the number of units of the product sold and p is the price, in dollars. What is the marginal revenue when 130 units of the product are sold? (2K, 2A) 6. Determine the equation of the tangent to y = -x (x+ 1)2 at x = -2 (3K, 3A) 7. A company sells an average of 50 skateboards per month at a price of $120 each. For each $5 decrease in price, two more skateboards are sold. Determine the marginal revenue when 25 skateboards are sold. (3A, 3T) 8. A beverage stand sells 500 smoothies per week at a price of $1.20 each. For every $0.10 decrease in price, the number sold per week increases by 20. The cost of smoothies is given by C(x) = 25 +0.12x + 0.001x. Determine the marginal profit when 200 smoothies are sold. (3A, 4T)