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
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Answer:
Step-by-step explanation:
Answer:
Equation → 5y = 3y + 6
Value of ST = 15
Step-by-step explanation:
From the picture attached,
In right triangles ΔVST and ΔVUT,
Acute angles ∠SVT ≅ ∠UVT [Given]
TV ≅ TV [By reflexive property of congruence]
ΔVST ≅ ΔVUT [Hypotenuse angle congruence of right triangles]
Therefore, corresponding parts of the congruent triangles are congruent.
Therefore, ST ≅ TU
5y = 3y + 6
5y - 3y = 6
2y = 6
y = 3
Therefore, ST = 5y
ST = 5(3)
= 15
