Question

The sum of the AP, 1+2+3+------+10=----​

Answer 1

$\bigstar\huge\bf\underline{\underline{Answer:-}}$

a=1

d= 2-1 = 1

l =10

Tn=10

Tn = a + (n-1)d

10 = 1 + (n-1) 1

10 -1 = (n-1)1 ( by multiplying 1 in n-1)

9= n-1

9+1=n

10 = n

now , put the formula of sum

Sn = n/2(a+l)

Sn= 10/2(1+10)

Sn = 5(11)

Sn = 55.

Therefore, the sum of the AP, 1+2+3+....+10 ⇒55

Answer 2

Step-by-step explanation:

s=n/2[2a +(n-1)×d]

sum = 10/2[2×1+(10-1)×1]

sum =5[2+9]

sum =5[11]

sum 55