sum of 20 terms of 3+6+12+
Answers
Answered by
1
a= 3
d = 3
Sn = n/2 [ 2a +(n-1)d]
=> S20 = 20/2 [ 2*3 + (20-1) 3]
=> S20 = 10 ( 6+19*3)
=> S20 = 10 * (6+57)
=> S20 = 10 * 63
=> S20 = 630
Sum of 20 terms = 630
d = 3
Sn = n/2 [ 2a +(n-1)d]
=> S20 = 20/2 [ 2*3 + (20-1) 3]
=> S20 = 10 ( 6+19*3)
=> S20 = 10 * (6+57)
=> S20 = 10 * 63
=> S20 = 630
Sum of 20 terms = 630
Deepti111:
hope u don't mind
its not so big mistake
its just an ans
nd u know its wrong
Actually I don't know about GP I have thought that they are in AP
I haven't studied GP yet
its okh
i think u r in 10 th std
yeah
it is the concept of 11 std.. sequence nd series chp
Answered by
2
it is in gp as 6/3=2 &12/6 =2 which is common ratio
so Tn= a(r raise to power n -1)/r-1
T20= 3(2 raise to power 20-1)/20-1
= 3(2 raise ti power 20-1)
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19
so Tn= a(r raise to power n -1)/r-1
T20= 3(2 raise to power 20-1)/20-1
= 3(2 raise ti power 20-1)
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19
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