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Which term of the A.P 3,15,27,39........will be 120 more than its 21st term ? |
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Answer» Hlw a=3d=12n=21an=?an=a + (n-1)d = 3+ 20d =3 + 20*12 = 3+240an =243An= an+ 120 = 243+120 =363An= a+(n-1)d 363= 3+(n-1)12363-3=(n-1)12360/12=n-130=n-1n =30+1n =31 |
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