Math, asked by atulshukla82944, 9 months ago

How many terms of the A.P. 55, 51, 47, ............. must be taken 50 that their sum is 405

Answers

Answered by Lokesh08
6

Answer:

Step-by-step explanation:

sum of n terms in ap= n/2(a+l)

where l=a+(n-1)d

405= n/2( 2*55-4(n-1))

by solving we get

2n^2-57n+405=0

2n^2-27n-30n+405=0

n=27/2 or n=15

number of terms cannot be a fraction so n=15

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