Question

Sum of 1st and 10th term of an arithmetic sequence is 100. Find the of 4th and 7th term​

Answer 1

Answer:

100

Step-by-step explanation:

let first term be 'a'

therefore,

10th term =a+9d

now, according to question

a+a+9d=100

=>2a+9d=100(i)

now,4th term=a+3d

7th term=a+6d

adding them we get

=2a+9d

=100(from(i)

Answer 2

Solution :-

Let us assume that, first term of given arithmetic sequence is a and common difference is d .

So,

→ T(n) = a + (n - 1)d

then,

→ T(1) + T(10) = 100

→ a + (a + 9d) = 100

→ 2a + 9d = 100 ---------- Eqn.(1)

therefore,

→ T(4) + T(7)

→ (a + 3d) + (a + 6d)

→ a + a + 3d + 6d

→ (2a + 9d)

putting value of Eqn.(1),

→ 100 (Ans.)

Hence, the sum of 4th and 7th term is also 100 .

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