1)
a) by considering the sum of the terms of an arithmetic series, show that

(1+2+...+n)^2 = n^2/4(n+1)^2

b) By using the principle of mathematical induction prove that

1^3+2^3+...+n^3 = (1+2+...+n)^2, for all n (greater or equal) to 1.

2)
Use mathematical induction to prove that, for every positive integer n,

13*6^n + 2 is divisible by 5.

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can someone show me how do you do it since the term is being squared i can't find the common difference and in 2 i can't make an equation.