Difference between successive terms = +4
27th term = a1 + (n-1)(d)
-15 + (26)(4) = 89
Sn = n (a1+a27)/2 = 27 (-15+89)/2 = 999
A LOT more legible than my answer ! LOL.....
If you are asked to factorize it, that is a good start....
((1/2x)^3 - 2^3 ) can you do it now?
Here is my scrawled answer..... basically I did the long division and found what values of A and B produce a zero remainder....
a+b = -99
Here is something that may clue you in......
Factoring a Difference of Cubes:
a3 – b3 = (a – b)(a2 + ab + b2)
x+y - z you have to subtract z from the total becuase you count them twice when you add x and y ....
Find y -intercept by setting x = 0 in the equation y = -1 plot that point (0,-1)
find x -intercept by setting y = 0 in the equation x = 1/2 plot that point (1/2, 0) draw the line through those two points....done.
https://web2.0calc.com/questions/help_22327#r5