DAnswer:
Step-by-step explanation:
25. <u>Step-by-step explanation:</u>


To find the foci, first we must find the length of the foci using the formula:

Then add the c-value to the h (or k)-value that represents the major.
b² - a² = c²
25 - 16 = c²
9 = c²
±3 = c
The center is (0, 0) and the major is the y-value so the foci is:
(0, 0+3) and (0, 0-3) ⇒ (0, 3) and (0, -3)
26. Answers
Follow the same steps as #25:
Center: (0, 0)
Vertices (7, 0) and (-7, 0)
Co-vertices: (0, 3) and (0, -3)
foci: (2√10, 0) and (-2√10, 0)
length of major: 14
length of minor: 6
9514 1404 393
Answer:
Tn = -4n² +40n +36
Step-by-step explanation:
A graphing calculator readily performs the quadratic regression, yielding the formula ...
Tn = -4n² +40n +36
__
The first and second differences of the given sequence terms are ...
28, 20, 12 and -8, -8
The coefficient of the squared term is half the second difference, so is -4. Then the sequence of squared terms is -4n²:
-4, -16, -36, -64
Subtracting these values from the original sequence gives the linear sequence ...
76, 116, 156, 196
which has first term 76 and common difference 40. The equation for the n-th term of this is ...
an = 76 +40(n -1) = 36 +40n
Adding this linear sequence to the sequence of squared terms, we get ...
Tn = -4n² +40n +36