IF IN A AP SERIES 18TH TERM IS 29 & 29TH TERM IS 18. THEN FIND THE 49TH TERM??

• 49th term is -2.
  
  18th term = a + 17d..........(i)
  
  29th term = a + 28d..........(ii)
  
  Solving equation i and ii, we got
  
  d = -1
  
  put d = -1 in any of the above equations and we will get, a = 46
  
  Now, we know 49th term can be written as, a + 48d
  
  now putting the value of a and d in the above equation,
  
  a + 48d = 46 + 48(-1)
  
  = 46 - 48
  
  = -2
• 10 years agoHelpfull: Yes(50) No(2)
• the 49th will be -2
  In AP
  18th term=>a+(18-1)d=29........(1)
  29th term=>a+(29-1)D=18........(2)
  here a and d has respective signifance
  then solve the equation 1 and 2
  then u will get a=46;d=-1
  then 49th term will be =>46+(49-1)(-1)=-2
• 10 years agoHelpfull: Yes(11) No(4)
• a+(18-1)d=29
  a+17d=29----(i)
  a+28d=18----(ii)
  Solving i and ii we get
  d=-1 and a=46
  for 49th term
  46+(49-1)*(-1)
  =-2
  
  
• 10 years agoHelpfull: Yes(0) No(0)
• can any one explain me how d=-1,a=46 is possible?
• 10 years agoHelpfull: Yes(0) No(0)
• nth term is = {a+(n-1)d}
  18th term is = a+(18-1)d ............. { n=18 }
  as 18th term is given to be 29 therefore
  a+(18-1)d = 29 .....eq.1
  
  similarly 29th term is {a+(29-1)d}
  ie. a+28d= 18......eq.2 ( 29th term is given to be 18 )
  
  so equating eq.1 and eq.2 we get
  (a+17d)- (a+28d) = 29-18
  
  which gives d=-1,
  putting value of d=-1 in eq.1
  we get a=46
  
  49th term is a+(49-1)d= 46+(48)* -1
  ie. -2 = ans
• 10 years agoHelpfull: Yes(0) No(0)