If 7 times the 7th term is equal to the 11 times the 11th term. prove that its 18th term is zero

If 7 times the 7th term is equal to the 11 times the 11th term. prove

1.	If 7 times the 7th term is equal to the 11 times the 11th term. prove that its 18th term is zero
Answer» Thanks garauv bhai.. whr frm u 7th term = (a+6d) 11th term = (a+10d)(a+6d)7=(A+10d)11 (given)7a + 42d =11a +110d (on solving)7a - 11a = 110d - 42d-4a = -68da= -17dwe know 18th term = (a+17d)........................... (i)now we substitute the value of a in (i)\xa0which emplies, -17d + 17d = 0hence proved