The distributive law from algebra states that for real numbers

c, a1 and a2, we have c(a1 + a2) = c a1 + ca2


Use this law and mathematical induction to prove that, for all


natural numbers, n ≥ 2, if c, a1, a2, …... an are any real numbers,


then c(a1 + a2 +…+ an) = c a1 + c a2 +…+ c an.

Let P(n):c(a1+a2+…+an) = ca1+ca2+…+can ,for all natural


numbers, n ≥ 2.


Step1: For n=2,


P(2)


LHS= c(a1 + a2)


RHS= c a1 + ca2


As, it is given that c(a1 + a2) = c a1 + ca2


Thus, P(2) is true.


Step2: For n=k,


Let P(k) be true


So, c(a1+a2+…+ak) = ca1+ca2+…+cak


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


P(k+1):


LHS= c(a1+a2+…+aK+ak+1)


=c[(a1+a2+…+aK)+ak+1]


=c(a1+a2+…+aK)+cak+1


=ca1+ca2+…+caK+cak+1


=RHS


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


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