Question

which term of the A.P 5/2,4,11/2,....is31? find also the 10 th term

Answer 1

t1=5/2
t2= 4
t3=11/2
d=t2-t1
d=4-5/2
=8-5/2
d=3/2
tn=31
tn=a+(n-1)d
31=5/2+(n-1)3/2
31-5/2=3n/2-3/2
62-5/2=3n/2-3/2
57/2+3/2=3n/2
30=3n/2
30*2/3=n
20=n
t20=31
t10=?
tn=a+(n-1)d
t10=5/2+(10-1)3/2
t10=5/2+9*3/2
=5/2+27/2
t10=32/2
t10=16.....plz mark it as brainliest..

Answer 2

put ALL formula for n terms
31=5/2+(n-1) 3/2
(n-1) 3/2=31-5/2
(n-1) 3/2=57/2
n-1=(57/2) ×(2/3)
n-1=19
n=19+1=20
thus, 20th term of an AP us 31
10th term=5/2+9×3/2
=32/2=16