Question

1) In an A.P if S10 = 35 and S9
= 28 find a10​

Answer 1

a10=Sn-Sn-1

=S10-S10-1

=S10-Sn

=35-28

a10=7

Answer 2

In an AP if S₁₀ = 35 and S₉ = 28 then a₁₀ = 7

Given :

In an AP S₁₀ = 35 and S₉ = 28

To find :

The value of a₁₀

Solution :

Step 1 of 2 :

Write down the given data

Here it is given that for an AP

S₁₀ = 35 and S₉ = 28

Step 2 of 2 :

Find the value of a₁₀

We have

aₙ = nth term of the AP

Sₙ = The sum of the first n terms of the AP

Thus we get

a₁₀

= 10th term of the AP

= ( a₁ + a₂ + a₃ + a₄ + a₅ + a₆ + a₇ + a₈ + a₉ + a₁₀ ) - ( a₁ + a₂ + a₃ + a₄ + a₅ + a₆ + a₇ + a₈ + a₉ )

= The sum of the first 10 terms of the AP - The sum of the first 9 terms of the AP

= S₁₀ - S₉

= 35 - 28

= 7

━━━━━━━━━━━━━━━━

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