Find the first 4 terms of the arithmetic sequence.
f(n) = f(n-1) + 5
f(1) = -2

f(n) = f(n-1) + 5   simply means

the next term or f(n), will have a value of
the one before it, or f(n-1), +5

so.. you're looking for the 4th term, that means f(4)
to get 4th term then, that will be the 3rd term plus 5,
whatever the 3rd term is

now... f(1) = -2, simply means, the term 1, or f(1), or first term, is -2

now to find a term value in an arithmetic sequence 

and I'm sure you know what f(1) is, so, just plug it in, to get f(4), or 4th term

1. isolate the variable, in this case, d. subtract 35.5 on both sides of the equation.2. 52 subtracted by 35.5 is 16.53. therefore your answer would be d= 16.5this is the basics of pre algebra, isolating variable through adding, subtracting, multiplying, and dividing, if you have any other questions to ask just comment!