Question

if 7 times the 7th term of an ap is equal to 4 times the fourth term , then prove it's 11th term is zero​

Answer 1

Answer:

How there! This answer might help you

Step-by-step explanation:

7 times the 7th term of an AP is

= a₇ x 7

= {a + (7 - 1) d} x 7

= 7a + 42d_____(i)

Also, 4 times the 4th term of an AP is

= a₄ x 4

= {a + (4 - 1) d} x 4

= 4a + 12d_____(ii)

Given that equation (i) and(ii) are equal

7a + 42d = 4a + 12d

7a - 4a = 12d - 42d

3a = -30d

a = -10d

Now to find its 11th term,

aₙ = a + (n-1) d

a₁₁ = -10d + (11 - 1) d

a₁₁ = -10d + 10d

a₁₁ = 0