Question

if 7 times the 7th term of an ap is equals to 11 times the 11th term show that 18th term of an ap is zero ​

Answer 1

Answer:

Target to prove : 18th term = 0

Step-by-step explanation:

• According to question,,
• 7.T7 =11.T11
• 7.[a+ ( 7-1).d] = 11.[a+(11-1).d]
• 7a +7.d.6= 11a+ 11.d.10
• (11a-7a) -+(110d -42d) = 0
• (4a +68d) = 0
• a +17d = 0
• SO,,

:. a= -17d

NOW,,,

18th term = a + ( 18 - 1). d

= -17d +17d

= 0

••••••••••• Hence : 18 th term if an A.P is equal to zero.

proved.

Answer 2

Answer:

Answer:  = 0.

Step-by-step explanation:

▶ Given :-

→ 7 = 11

▶ To prove :-

→    = 0 .

We have,

=> 7 = 11

=> 7( a + 6d ) = 11( a + 10d ) .

=> 7a + 42d = 11a + 110d .

=> 11a - 7a = 42d - 110d .

=> 4a = - 68d .

=> 4a + 68d = 0 .

=> 4( a + 17d ) = 0 .

=> a + 17d = 0/4 .

=> a + ( 18 - 1 )d = 0.

HOPE IT HELPS!