Question

sn formula class 10 AP

Answer 1

1) Sn= n/2 (2a+(n-1)d)
2) Sn= n/2 (a+l).
hope this helps you ^_^

Answer 2

Sₙ formula for A.P is n/2(a+aₙ) and the other one is n/2(2a+(n-1)d).

• The first formula is n/2(a+aₙ), where n is the number of terms, a is the first term of the A.P and aₙ is the nth term of the A.P.
• The second formula is n/2(2a+(n-1)d). Now, if we observe the first formula that is n/2(a+aₙ), where we can substitute the value of aₙ. The value of aₙ is a+(n-1)d, where a is the first term of the A.P, n is the number of terms and d is a common difference.
• So, substituting the value of aₙ, we get Sₙ = n/2(2a+(n-1)d). Hence, these are the formulas for calculating the sum of n terms of A.P.