I believe you are referring to exponents that have a multiple of three. If so any number * three is a valid exponent in your case.
Take the sequence in 1a
The 10th term is 31
The 20th is 61
If you wanted to find these by continuing the series, you'd have to add 3 to the last number in the series, then 3 more, then 3 more, until you reach the 20th term. By this point, you will have added 3 to the first term 19 times. That's where the formula comes from. So here,
a = 4, the first term
n = 20, the number of the term we need
d = 3, how much we're adding each time between one term and the next
Then, to get the 20th term,
4 + (20 - 1) • 3 = 4 + (19 • 3) = 4 + 57 = 61
Answers
The 10th and 20th terms of each sequences are
a. 31; 61
b. 48; 98
c. 47; 97
(in <em>c</em>, you're adding the same <em>d</em> as in the sequence above, but your first term is one unit less)
d. -25; -75
(same thing as before, but now, <em>d</em> is negative)
e. 11.5; 16.5
(with <em>d</em>=1/2 or 0.5)
f. 6+1/2; 8+1/2
Use these to check your answers after applying the formula, but know that I calculated on the fly and didn't check these.
Bob was 5 feet off the ground. He travels 4 feet every single second. How long will it take for him to reach 37 feet?
4x + 5 = 37
4x + 5 (-5) = 37 (-5)
4x = 32
4x/4 = 32/4
x = 8
It will take Bob ~8 seconds to reach 37 feet*
*Problem & answer
hope this helps
H(10) is the altitude of a hot air balloon overtime after 10 minutes. In order to find h(10)'s value, you just have to substitute 10 as t in the equation. h(10) and h(t) represents the value of y in a linear equation. So pretty much: h(10)= 210 - 15(10). If calculated correctly, h(10)=60.
3/4 is 0.75 as a decimal so 4 x 0.75 = 3
