In an ap givan a=7,a13=35 find d and s13
Anonymous:
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Answers
Answered by
439
Hello Friend
as you have given
a=7
a¹³ = 35 it means no of terms = 13
so n = 13.
we know
aⁿ = a+(n-1)d
so put the values .----
35 = 7 +(13-1)d
28 = 12d
so
d = 28/12 => 7/3
Now sⁿ = n/2(a+aⁿ)
hence we get
sⁿ = 13/2(7+35)
=> 13/2(42)
=>21×13
=> 273
.
as you have given
a=7
a¹³ = 35 it means no of terms = 13
so n = 13.
we know
aⁿ = a+(n-1)d
so put the values .----
35 = 7 +(13-1)d
28 = 12d
so
d = 28/12 => 7/3
Now sⁿ = n/2(a+aⁿ)
hence we get
sⁿ = 13/2(7+35)
=> 13/2(42)
=>21×13
=> 273
.
Thanku
my pleasure
Answered by
154
Answer:
Step-by-step explanation:
Hello, friends
It is given that :
a=7, a13=35 &to find d&s13
a13=35
a+12d=35
a=7
7+12d=35
12d=35-7
12d=28
d=28/12
d=7/3
sn=n/2(a+an)
s13=13/2(7+35)
=13/2(42)
=13(21)
s13=273
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