Two twin sisters are away at college. They both called home today. Tara calls home every 4 days. Sara calls home every 3 days. H
1 answer:
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Answer:
Option A is correct.
Value of
Step-by-step explanation:
Given: and common difference(d) = 3.4
A sequence of numbers is arithmetic i.e, it increases or decreases by a constant amount each term.
The sum of the nth term of a arithmetic sequence is given by;
, where n is the number of terms, a is the first term and d is the common difference.
We also know the nth tern sequence formula which is given by ;
......[2]
First find a.
it is given that
Put n =12 and d=3.4 in equation [2] we have;
2.4 = a + 37.4
Simplify:
a = - 35
Now, to calculate
we use equation [1];
here, n =2 , a =-35 and d=3.4
Simplify:
Therefore, the sum of sequence of 22nd term i.e,
Answer:
S₉ = 255.5
Step-by-step explanation:
the sum to n terms of a geometric sequence is
=
where a₁ is the first term and r the common ratio
here a₁ = 0.5 and r = =
= 2 , then
S₉ =
=
= 0.5(511)
= 255.5