Answer:
30th term is
9(30+3) =270+27=297
to find the first term which is larger than 100
9(n+3) =100
9n=100-27
9n=73
n=73÷9
=8.1
so when n is>8.1 all the terms will be larger than 100 and the first term will be 9 since n can't be fraction as it's an ordinary number
so it's 9th
9(9+3) =81+27=108
the first four terms are
9(1+3) =36
9(2+3) =45
9(3+3) =81
9(4+3) =63
Explanation:
n(n-1)
the first four terms are
1(1-1) =0
2(2-1) =2
3(3-1) =6
4(4-1) =12
the 10th term is 10(10-1) =90
to find weather 51 is a term or not
n(n-1) =51
n^2-n-51=0
1-4×1×-51=1+204=205
so it's roots will be fraction
so it's not from its terms because n will
be fraction
to find the term 182
n(n-1) =182
n^2-n-182=0
(n-14) (n+13)=0
so it's the term 14th because n can't be negative