Answer:
case a)
----> open up
case b)
----> open down
case c)
----> open left
case d)
----> open right
Step-by-step explanation:
we know that
1) The general equation of a vertical parabola is equal to

where
a is a coefficient
(h,k) is the vertex
If a>0 ----> the parabola open upward and the vertex is a minimum
If a<0 ----> the parabola open downward and the vertex is a maximum
2) The general equation of a horizontal parabola is equal to

where
a is a coefficient
(h,k) is the vertex
If a>0 ----> the parabola open to the right
If a<0 ----> the parabola open to the left
Verify each case
case a) we have

so


so

therefore
The parabola open up
case b) we have

so



therefore
The parabola open down
case c) we have

so



therefore
The parabola open to the left
case d) we have

so



therefore
The parabola open to the right
Answer: The required fourth term of the geometric sequence is 
Step-by-step explanation: We are given to find the value of the fourth term in a geometric sequence with first term and common ratio as follows :

We know that
the n-th term of a geometric sequence with first term a1 and common ratio r given by

Therefore, the fourth term of the given geometric sequence will be
Thus, the required fourth term of the geometric sequence is 
Answer:
- 216/25
8 16/25
8.64
Step-by-step explanation: