Complete the recursive formula of the arithmetic sequence 20, 26, 32, 38, a(1) = ?
a(n) = a(n − 1)+ ?

The suare root of 9x plus 7 plus the square rot of 2x equall to 7

I’ve been trying all day to figure this puzzle out. i need the work for it aswell. it is a factoring polynomials tarsia. the image is below.

Atourist boat is used for sightseeing in a nearby river. the boat travels 2.4 miles downstream and in the same amount of time, it travels 1.8 miles upstream. if the boat travels at an average speed of 21 miles per hour in the still water, find the current of the river.