anonymous one year ago Use mathematical induction to prove the statement is true for all positive integers n. The integer n3 + 2n is divisible by 3 for every positive integer n.

1. IrishBoy123

1] test for n = 1 2] assume true for k = 1 so assumed $$\frac{k^3 + 2k}{3} \in Z$$ 3] now see what you can do with $$\frac{(k+1)^3 + 2(k+1)}{3}$$, ie with k replaced by k+1 i simply expanded out the numerator and it just came together

2. anonymous

thank you