9. a submarine dove 400 feet. it then
rose at a rate of 20 feet per minute.
what was the depth of the submarine
after 18 minutes?
d
is

hello from mrbilldoesmath!

answer:

a(n) - a(n-1) -3

discussion:

this ones a bit interesting. given a(n) = 5 - 3n consider this:

a(n-1) = 5 - 3(n-1)

          = (5 - 3n) + 3             => but a(n) = 5 - 3n, the first term

          = a(n)   + 3                 => subtract 3 from both sides

a(n-1) -3 = a(n)  

or

a(n) - a(n-1) -3

you,

mrb

168

step-by-step explanation:

i am pretty sure that the answer is 168

18.75 gallons

step-by-step explanation: