2x^2 + 5x – k=0 In the equation above, k is a constant. For what value of k does the equation have exactly one
distinct real solution?

I don’t understand the khan academy explanation

What is the distance between point a and b

Meghan has created a diagram of her city with her house, school, store, and gym identified. a. how far is it from the gym to the store? b. meghan also wants to walk to get some exercise, rather than going to the gym. she decides to walk along arc ab. how far will she walk? round to 3 decimal places.

Out of $20$ creepy-crawly creatures in a room, $80\%$ are flies and $20\%$ are spiders. if $s\%$ of the total legs belong to spiders, what is $s$?