1.

Prove by the principle of mathematical induction:(ab)n = an bn for all n ϵ N

Answer»

Suppose P (n): (ab)n = an bn 

Now let us check for n = 1,

P (1): (ab)1 = a1 b1

: ab = ab

P (n) is true for n = 1.

Then, let us check for P (n) is true for n = k, and have to prove that P (k + 1) is true.

P (k): (ab)k = ak bk … (i)

Now we have to prove,

(ab)k + 1 = ak + 1.bk + 1

Therefore,

= (ab)k + 1

= (ab)k (ab)

= (abk) (ab) using equation (1)

= (ak + 1) (bk + 1)

P (n) is true for n = k + 1

Thus, P (n) is true for all n ∈ N.



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