for all natural number n.
P(n)=
Now, we’ll substitute different values for n,
P(1) = 1
= 1(2-1), is true
P(2) = 1+5 = 6
= 2(4-1), is true
Now, let us consider,
Thus, P(k+1) is true if P(k) is true
Hence, by mathematical induction,
For each natural no. n it is true that, P(n)=