8 + 2(10 - r) = 8 + 20 - 2r = 28 - 2r
First simplify the equation and next multiply the 20 with the x^2 and find a number that adds together to give you the middle
Answer:
-4
Step-by-step explanation:
The number that is by itself is always the y-intercept
First term is -7, so a_1 = -7
To get the next term, we add on 4. We can see this if we subtract like so
d = (2nd term) - (1st term) = (-3) - (-7) = -3+7 = 4
So d = 4 is the common difference.
Apply a_1 = -7 and d = 4 to get...
a_n = a_1 + d*(n-1)
a_n = -7 + 4*(n-1)
a_n = -7 + (n-1)*4
Answer: Choice A
