The 4th term of an AP is 13 and the 10th term is 31. Find the 30th term.
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a4=13
a+3d=13. .........(1)
a10=31
a+9d=31. ............(2)
subtracting eq(2)from eq(1)
a+3d=13
a+9d=31
(-) (-) (-)
-6d=-18
d=18/6
d=3
putting d=3 in eq (1)
a+3d=13
a+3(3)=13
a+9=13
a=13-9
a=4
a30=a+29d
=4+29(3)
=4+87
=91
hence ,the 30th term of an ap is 91
hope this answer will be helpful........
a+3d=13. .........(1)
a10=31
a+9d=31. ............(2)
subtracting eq(2)from eq(1)
a+3d=13
a+9d=31
(-) (-) (-)
-6d=-18
d=18/6
d=3
putting d=3 in eq (1)
a+3d=13
a+3(3)=13
a+9=13
a=13-9
a=4
a30=a+29d
=4+29(3)
=4+87
=91
hence ,the 30th term of an ap is 91
hope this answer will be helpful........
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