Step-by-step explanation:
rate of change is the 1st derivative
f'(x)=3×12×dx/dx
f'x=36
Answer:
given
n=9
a=1
d=3-1=2
now , by formula,
sn = n/2(2a+(n-1)d)
= 9/2(2×1+(9-1)×2)
=9/2×18
=81
Find the question mark using the model I've provided and that'll be the answer!