Question

If 1,2,3 ..... are in ap then the sum of first 120 terms

Answer 1

Step-by-step explanation:

No. of terms = 120

Common difference = 2 - 1 = 1

First term = 1

Sum of 120 terms

= n/2 (2a + (n - 1) d)

= 120/2 (2 × 1 + (120 - 1) 1)

= 60 (2 + 119)

= 60 × 121

= 7260

Answer 2

$\huge{\boxed{\underline{\underline{\mathbb{\red{ANSWER}}}}}}$

$\large{\boxed{\sf sum\:7260}}$

Step-by-step explanation:

a=1, d=2-1=1,. n=120

S120=n/2{2a+(n-1)d}

=120/2{2x1+(120-1)1}

=60x121

=7260

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