1.

Find 20th term from the last term of the AP 3,8,13 ,253

Answer» 158
a=3 ,d=(8-3)=5 ,l=253Tn = l -(n-1)dT20= 253 -(20-1)5 =253-19*5 =253-95 = 158
a=253,d=5 but for the last term d=-5 a+(n-1)d. =253+(20-1)(-5). =253+(19)(-5)253-95 =158
158
Ap=3,8,13...............253a=3d=8-3=5a20=a+19da20=3+19×5a20=3+95a20=98_______________


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