If P(n) is the statement “n(n + 1) is even”, then what is P(3)?
11n+2 + 122n+1 is divisible by 133 for all n ϵ N
Let P(n) = 11n+2 + 122n+1
Now, P(n): 11n+2 + 122n+1 is divisible by 133 for all n ϵ N
Step1:
P(1) = 1331 + 1728 = 3059
Thus, P(1) is divisible by 133
Step2:
Let, P(m) be divisible by 24
Then, 11m+2 + 122m+1 = 133λ, where λ ϵ N.
Now, we need to show that P(m+1) is true whenever P(m) is true.
So, P(m+1) = 11m+3 + 122m+3
= 11m+2.11+ 122m+1.122+11.122m+1 – 11.122m+1
= 11.(11m+2+ 122m+1) + 122m+1(144-11)
= 11.133λ + 122m+1.133
= 133.(11 λ + 122m+1)
Thus, P(m+1) is true.
So, by the principle of mathematical induction, P(n) is true for all n ϵN.