Series calcular s=1+2+3++86

S = 3741

Step-by-step explanation:

Here, we want to calculate the sum of the first 86 numbers (starting from 1)

Mathematically, we can use the formula;

Sn = n/2[ a + L]

Where n is the number of terms (86 here)

a is the first term which is 1 and L is the last term which is 86

So, we have the sum as;

Sn = 86/2(1 + 86) = 43 * 87 = 3741

2nd one in the first row is correct

s

step-by-step explanation: