Hey there!!
Recursive formula :
... a( n ) = a ( n - 1 ) + 7
The first term is 12
To find the second term, we will need to substitute 2 in place of ' n '
2 term :
... a( 2 ) = a ( 2 - 1 ) + 7
... a( 2 ) = a( 1 ) + 7
We know a( 1 ) = 12
... a( 2 ) = 12 + 7
... 19 is the second term and we will need to use this to find the other terms.
Hope my answer helps!
You have the following function:

Derivate implictly the previous expression, as follow:

Where you have used that:

Then, the implicit derivative of the given expression is:

Next, solve for y' as follow:

From the little marks on the sides, we can see that YZ is the midpoint segment.
YZ is half of VX
12.2 is the answer.
Speed of the ship in the second hour = (62.5 * x ) / 100 kph.
In third hour it is [(62 * x) / 100 ] * x/100]
is 4th hour its is the above * x/100 again so we can now form the equation
62.5x x x
------- * ---- * ---- = 32
100 100 100
62,5 x^3 = 32,000,000
x^3 = 512,000
x = 80 <----- Answer to (a)
(b) Ship travels 62.5 in first hour then this falls by a common ratio of 0.8 each hour so we have a geometric sequence
Dist travelled in 6 hours = a1 1 - r^n
-------- = 62.5* (1 - 0.8^6) / 1 -0.8 = 230.56
1 - r
Answer is 230.56 km
You would put 9 times v because you are multiplying it to the 9 and you do not know what v is then you would divide it by 3 and get your answer so for example if you should have gotten 9 times v = 72 then 72 divided by 3 = 24 and 24 divided by 3 = 8