​Prove 2.32 +22.33 +23.34 +… +2n​.3​n+1 = 18/5 (6n -1) by the principle of mathematical induction for every nєN. 

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Let the given statement be Pnie Pn:2.32+22.33+23.34+...+2n.3n+1=1856n-1For n=1, we haveP1:2n.3n+1=21×31+1=2×32=18and 18561-1=185×5=18 which is true.Let Pk be true for some postive integer k ie2.32+22.33+23.34+...+2k.3k+1=1856k-1     ...(1)We shall now prove that Pk+1 is true2.32+22.33+23.34+...+2k.3k+1+2k+1.3k+1+1 =2.32+22.33+23.34+...+2k.3k+1+2k+1.3k+2=1856k-1+2k+1.3k+2     [using 1]=2×326k-1+5×2k+1.3k+25=2k+1×3k+2-2×32+5×2k+1.3k+25=2k+1×3k+21+5-185=2k+1×3k+2×6-185=2k+2×3k+3-185=2k×4×3k×27-185=6k×108-185=1856k×6-1=1856k+1-1Thus P(k+1) is true whenever  P(k) is true.Hence by PMI, statement P(n) is true for all nN.
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