You do the sum backwards,
36-16=17
17x3=51
Then you check it to make sure,
51/3=17
17+19=36
:) hope this hepled x
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:
brainly.com/question/25749583
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(6x-1)+20+(x+14)=180
6x-1+20+x+14=180
6x+x+20+14-1=180
7x+33=180
-33 -33
7x=147
7/7x=147/7
x=21
Measure of angle A=:
(6x-1)
6x-1
6(21)-1
126-1
125
Measure of angle A is 125°
Measure of angle C=
(x+14)
x+14
21+14
35
Measure of angle C is 35°
What’s the question? I don’t have enough info.
