Can someone please check my answer?

For x≥0, √x⁵ + √9x =

(A) (x²+ 3)√x (This is the answer I got, is it correct? If it's not, can you please explain to me the correct process to get the right answer?)

(B) 10√x⁶

(C)√(x⁵+ 9x)

(D)x²+ 3

(E) 3x²

The probability that a student graduating from suburban state university has student loans to pay off after graduation is .60. if two students are randomly selected from this university, what is the probability that neither of them has student loans to pay off after graduation?

Someone answer asap for ! a discount store’s prices are 25% lower than department store prices. the function c(x) = 0.75x can be used to determine the cost c, in dollars, of an item, where x is the department store price, in dollars. if the item has not sold in one month, the discount store takes an additional 20% off the discounted price and an additional $5 off the total purchase. the function d(y) = 0.80y - 5 can be used to find d, the cost, in dollars, of an item that has not been sold for a month, where y is the discount store price, in dollars. create a function d(c(x)) that represents the final price of an item when a costumer buys an item that has been in the discount store for a month. d(c(x)) =

How do you determine if an ordered pair is a solution to a given equation?