how many term of the series 2+4+6+......Amount to 42?
Adwita:
I could not understand this.
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Answered by
6
2+4×6+8+10+12=42 is your answer.
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okk
thats the trick
i was not understanding
ok
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there no option to mark u as a brainliest...
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sn=n/2(2a+(n-1)×2 formula h plz solve....
Answered by
4
Heya user,
I'd avoid to use
Formula...
So, rather .... 2 [ 1 + 2 + 3 + .... ] = 42
=> [ 1 + 2 + ... ] = 21
=> n ( n + 1 )/2 = 21
=> n ( n + 1 ) = 42
=> n² + n - 42 = 0
=> ( n + 7 ) ( n - 6 ) = 0;
=> n = 6 <-------- [ neglecting negative value ]
So, there are 6 terms in the series to add to get '42' where the last term = 2 * 6 = 12
I'd avoid to use
So, rather .... 2 [ 1 + 2 + 3 + .... ] = 42
=> [ 1 + 2 + ... ] = 21
=> n ( n + 1 )/2 = 21
=> n ( n + 1 ) = 42
=> n² + n - 42 = 0
=> ( n + 7 ) ( n - 6 ) = 0;
=> n = 6 <-------- [ neglecting negative value ]
So, there are 6 terms in the series to add to get '42' where the last term = 2 * 6 = 12
:) Plz Mark Brainliest
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