Math, asked by zuni2023, 1 year ago

The sum up to n terms of an A. P. is 48, first term is 20 and common difference is -4 . find the number of terms.

Answers

Answered by geetsharu1234
1

48=20+(n-1)-4

48-20=(n-1)-4

28/-4=(n-1)

-7+1=n

-6=n


Answered by riyaswaroop
1

As we know,

Sn=n/2[2a+(n-1)*d]

Here, a=20, d=-4 ,Sn=48

Therefore,

48=n/2[44-4n]

48=n[22-2n]

2n^2 - 22n +48=0

Now, solve this quadratic...,

Whatever will be the value of n... Will be the required number of terms.....


Hope it helps you.....

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