Question

If 7 times a7 is equal to 11 times a11, then find the 18th term

Answer 1

Hey there !!

Given :-

→ 7( a₇ ) = 11( a₁₁ ) .

To find :-

→ a₁₈ = ? .

Solution :-

We have,

⇒ 7( a₇ ) = 11( a₁₁ ) .

⇒ 7( a + 6d ) = 11 ( a + 10d ) .

⇒ 7a + 42d = 11a + 110d .

⇒ 42d - 110d = 11a - 7a .

⇒ - 68d = 4a .

⇒ 4a = -68d .

⇒ 4a + 68d = 0 .

⇒ 4( a + 17d ) = 0 .

⇒ a + 17d = 0/4 .

⇒ a + 17d = 0 .

⇒ a + ( 18 - 1 )d = 0 .

∴ a₁₈ = 0 .

Hence, 18th term of the AP is 0 .

THANKS.

#BeBrainly .