which term of an ap 3, 15 15, 27, 39 ..... will be 120 more that its 21st first term
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a =3, d 15-3 =12
ATQ,
a21= an+120
a+20d= a+(n-1)d+120
3+20(12)=3+(n-1)12+120
3+240=3+12n-12+120
243=12n-111
243-111=12n
132=12n
n=11
11th term will be 120 more than its 21st term.
ATQ,
a21= an+120
a+20d= a+(n-1)d+120
3+20(12)=3+(n-1)12+120
3+240=3+12n-12+120
243=12n-111
243-111=12n
132=12n
n=11
11th term will be 120 more than its 21st term.
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