A sequence x0, x1, x2, x3, …. is defined by letting x0 = 5 and

xk =4+xk–1 for all natural numbers k. Show that xn = 5 for all


nϵN using mathematical induction.

Let P(n): xn =5+4n for all nϵN


Step1: For n=0,


P(0):x0=5+4×0=5


So, it is true for n=0.


Step2: Let P(k) be true


Thus, xk =5+4k


Now, we need to show P(k+1) is true whenever P(k) is true.


P(k+1):


xk+1 =4+ xk+1-1


=4+xk


=4+5+4k


=5+4(k+1)


=RHS


Thus, P(k+1) is true, so by mathematical induction P(n) is true.


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