What is the common difference in the sequence 9, 4, -1, -6?

a. 5

b. -5

c. 9

d. -11

(am i dividing or subtracting? )

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 +"

Could somebody me with this radical simplification?

Given the equation −4  = 12, solve for x and identify if it is an extraneous solution.