Question

In an AP if a=1,an=20 & Sn=336 than value of n​

Answer 1

n=32

Step-by-step explanation:

a=1

an=20

sn=336

Then,

=>an=a+(n-1)d

20=1+(n-1)d

19=(n-1)d

Also given,

$sn = \frac{n}{2} (2a + (n - 1)d)$

Substituting values,

336×2=n(2+21)

=>672=n(21)

n=32