The sum of the first 20 terms of an arithmetic sequence with the 18th term of 8.1 and a common difference of 0.25 is 124.5
Given,
18th term of an arithmetic sequence = 8.1
Common difference = d = 0.25.
<h3>What is an arithmetic sequence?</h3>
The sequence in which the difference between the consecutive term is constant.
The nth term is denoted by:
a_n = a + ( n - 1 ) d
The sum of an arithmetic sequence:
S_n = n/2 [ 2a + ( n - 1 ) d ]
Find the 18th term of the sequence.
18th term = 8.1
d = 0.25
8.1 = a + ( 18 - 1 ) 0.25
8.1 = a + 17 x 0.25
8.1 = a + 4.25
a = 8.1 - 4.25
a = 3.85
Find the sum of 20 terms.
S_20 = 20 / 2 [ 2 x 3.85 + ( 20 - 1 ) 0.25 ]
= 10 [ 7.7 + 19 x 0.25 ]
= 10 [ 7.7 + 4.75 ]
= 10 x 12.45
= 124.5
Thus the sum of the first 20 terms of an arithmetic sequence with the 18th term of 8.1 and a common difference of 0.25 is 124.5
Learn more about arithmetic sequence here:
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X - 1 < = 9 or 2x > = 24
x < = 9 + 1 x > = 24/2
x < = 10 x > = 12
closed circle on 10, shaded to the left
closed circle on 12, shaded to the right
________10_______12__________
<====X X======>
the X represents closed circles
I’m not sure what you are trying to say in this problem?
F(x) = kx
12 = 8k
k = 12/8 = 3/2
Required equation is f(x) = 3/2 x
9514 1404 393
Answer:
7 7/8
Step-by-step explanation:
There are several ways to get there.
2.25×3.5 = 7.875 = 7 7/8
(2 1/4)(3 1/2) = (9/4)(7/2) = 63/8 = 7 7/8
(2 1/4)(3.5) = 2(3.5) +(1/4)(3.5) = 7 + (2·3.5)/(2·4) = 7 +7/8 = 7 7/8
A typical graphing calculator will let you enter this problem directly, giving you a result either as a decimal, improper fraction, or a mixed number.
