Find S20 of the series whose first terms are: 30, 22, 14, 6, ...
1 answer:
Answer:
- 920
Step-by-step explanation:
There is a common difference d between consecutive terms in the sequence, that is
d = 22- 30 = 14 - 22 = 6 - 14 = - 8
This indicates the sequence is arithmetic with sum to n terms given by
=
[ 2a₁ + (n - 1)d ]
where a₁ is the first term and d the common difference
Here a₁ = 30 and d = - 8 , thus
=
[ (2 × 30) + (19 × - 8) ]
= 10(60 - 152)
= 10 × - 92
= - 920
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Answer:
option 1) 50
Step-by-step explanation:
Let m and w denote the men and women respectively.
From the question, if the groom invited w number of women, then bride invited 2w number of women.
Also, if the bride invited m number of men,then the groom invited 2m.
Hence we can write the following maths equation:
w+2m=105.........1
2w+m=135.........2
We multiply eqn(1) by 2 to get eqn(3)
This implies that,
2w+4m=210.......3
We then subtract eqn (2) from eqn(3) to obtain;
3m=75
we divide through by 3
Substituting the value of m into eqn (1)
to find the value for w
subtracting 50 from both sides.
So we can say the :
bride invited 25 men and 110 women,
groom invited 50 men and 55 women.