Answer: First Option : Sₙ= n/2(a₁ + aₙ)
Step-by-step explanation:
The nth partial sum of an arithmetic sequence or the sum of the first n terms of the arithmetic series can be defined as the sum of a finite number of term in an arithmetic sequence.
It is calculated using the formula:
Sₙ= n/2(a₁ + aₙ)
Where :
a₁ = First term
aₙ = last term
n = number of terms
Answer:
1. 50 m
2. 80 cm
Step-by-step explanation:
1. There are 2 triangles, subtract the area of 1 of them from the other.
The triangle that needs to be subtracted: b = 20 m, h = 10 m
A = 1/2b * h = 1/2(20) * 10 = 10*10 = 100 m
The big triangle, the one that needs to be subtracted plus the one you need to find the area of: b = 20 cm, h = 15 cm, 1/2(20) * 15 = 10 * 15 = 150
150 - 100 = 50 c
2. Divide it into 3 parts:
1- 3*4 = 12
2. 7*(4 + 4) = 7*8 = 56
3. [(4 + 4) * (13 - 7 - 3)]/2 = (8*3)/2 = 24/2 = 12
12 + 56 + 12 = 80 cm
Answer:
C
Step-by-step explanation:
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