Math, asked by clevseq, 11 months ago

Find the number of terms of the AP 6,9,12,...............so that their sum is 627

Answers

Answered by MaheswariS
13

Answer:

n=19

Step-by-step explanation:

Formula used:

The sum of n terms of an A.P a, a+d, a+2d,.... is

S_n=\frac{n}{2}[2a+(n-1)d]

Given A.P is

6, 9, 12...............

Here, a=6, d=3

Given:

S_n=627

\frac{n}{2}[2a+(n-1)d]=627

\frac{n}{2}[2(6)+(n-1)3]=627

n[12+3n-3]=1254

n[9+3n]=1254

3n[3+n]=1254

n[3+n]=418

n^2+3n-418=0

(n+22)(n-19)=0

n=-22,19

But n cannot be negaative

\therefore\:n=19

Answered by arpita7231
6

Step-by-step explanation:

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