Answer:
under the condition of f(x)=x composite function is an identity one
Remark
I'm going to interpret this equation as
D = ut + kt² The only difference is the 2.
Solution
Subtract kt² from both sides.
D - kt² = ut Now divide by u on both sides.

The t's cancel out. on the right. You are left with u on the right.

Answer:
-14
Step-by-step explanation:
You've got a(1)=20
a(1) means a(n) when n=1
the sequence is telling you to take the previous value of a(n), which is a(n-1) and subtract 17
then:
a(2) = a(1)-17 = 20 - 17 = 3
a(3) = a(2) - 17 = 3-17 = -14