Whats 1+2+3+4+5 add them together pls

Which is the equation of an ellipse with directrices at x = ±4 and foci at (2, 0) and (−2, 0)?

11. a particular type of cell doubles in number every hour. which function can be used to find the number of cells present at the end of h hours if there are initially 4 of these cells? a. n = 4 ()" b. n = 4(2)" c. n = 4 + (2)" din = 4 +"

Using only the digits 5, 6, 7, 8, how many different three digit numbers can be formed if no digit is repeated in a number?