# divisibility proof by induction

Prove $$n(n+2)$$ is divisible by $$4$$ by mathematical induction, if $$n$$ is any even positive integer. In this post, we will explore mathematical induction by understanding the nature of inductive proof, including the ‘initial statement’ and the inductive step. $$\require{color} \color{red} \ \ \text{ 0 is the first number for being true.}$$$$5^0 + 2 \times 11^0 = 3$$, which is divisible by $$3$$.Therefore it is true for $$n=0$$.Step 2:  Assume that it is true for $$n=k$$.That is, $$5^k + 2 \times 11^k = 3M$$.Step 3:  Show it is true for $$n=k+1$$.That is, $$5^{k+1} + 2 \times 11^{k+1}$$ is divisible by $$3$$.\begin{aligned} \displaystyle \require{color}5^{k+1} + 2 \times 11^{k+1} &= 5^{k+1} + 2 \times 11^k \times 11 \\&= 5^{k+1} + (3M-5^k) \times 11 \ \ \ \ \color{red} 2 \times 11^k = 3M – 5^k \ \ \ \text{ by assumption at Step 2} \\&= 5^k \times 5 +33M – 5^k \times 11 \\&= 33M – 5^k \times 6 \\&= 3(11M – 5^k \times 2), \text{ which is divisible by 3} \\\end{aligned}Therefore it is true for $$n=k+1$$ assuming that it is true for $$n=k$$.Therefore $$5^n + 2 \times 11^n$$ is always divisible by $$3$$ for $$n \ge 0$$. 2. $$\require{color} \color{red} \ \ \text{ 1 is the smallest odd number.} = 3[m + (k(k + 1) â 2)], which is divisible by 3. 60+4=5, which is divisible by 5 Step 2: Assume that it is true for n=k. Show it's true for n = 1, i.e. Divisibility Proof by mathematical induction !? Prove 6n+4 is divisible by 5 by mathematical induction. That is, 6k+4=5M, where M∈I. 2. 3. Mathematical Induction: Divisibility This is part of the HSC Mathematics Extension 1 course under the topic Proof by Mathematical Induction. Favorite Answer. Step 1: Show it is true for \( n=0$$. As … Let us assume that P(n) is true for some natural number n = k. or K3 â 7k + 3 = 3m, mâ N         (i). Thanks for any help. Mathematical Induction: Divisibility This is part of the HSC Mathematics Extension 1 course under the topic Proof by Mathematical Induction. Induction proof - divisibility by 3. 1. Mathematical Induction Divisibility can be used to prove divisibility, such as divisible by 3, 5 etc. Prove that 4^n + 6n -1 is diisible by 9 for all n>=1. That is, 6k+1+4=5P, where P∈I. Can someone help please? Prove $$4^n + 5^n + 6^n$$ is divisible by $$15$$ by mathematical induction, where $$n$$ is odd integer. For the sequence a n = a n-1 + 2n with a 1 = 1, a n is always odd. Then P(k) : 10k + 3.4 k+2 + 5 is divisible by 9. 2. 3 Answers. Absolute Value Algebra Arithmetic Mean Arithmetic Sequence Binomial Expansion Binomial Theorem Chain Rule Circle Geometry Common Difference Common Ratio Compound Interest Cyclic Quadrilateral Differentiation Discriminant Double-Angle Formula Equation Exponent Exponential Function Factorials Functions Geometric Mean Geometric Sequence Geometric Series Inequality Integration Integration by Parts Kinematics Logarithm Logarithmic Functions Mathematical Induction Polynomial Probability Product Rule Proof Quadratic Quotient Rule Rational Functions Sequence Sketching Graphs Surds Transformation Trigonometric Functions Trigonometric Properties VCE Mathematics Volume. $$\require{color} \color{red} \ \ \text{ Odd numbers increase by 2.} So, by the principle of mathematical induction P(n) is true for all natural numbers n. Use induction to prove that 10n + 3 Ã 4n+2 + 5, is divisible by 9, for all natural numbers n. P(1) ; 10 + 3 â 64 + 5 = 207 = 9 â 23. Prove \( 6^n + 4$$ is divisible by $$5$$ by mathematical induction, for $$n \ge 0$$. We have to to prove that P(k+1) is divisible by 9 for. Proving divisibility of expression using induction. I know that most of these types of problems have fairly straightforward proof-by-induction solutions -- but for this particular problem, I don't know how to finish the inductive step. Prove $$5^n + 2 \times 11^n$$ is divisible by $$3$$ by mathematical induction. Thus, P(k + 1) is true whenever P(k) is true. The specific questions is Prove by induction that n^3-7n+9 is divisible by 3 for all positive integer n My approach, which afaict differs from t Step 1:  Show it is true for $$n=1$$. Answer Save. Apart from the stuff given above, if you need any other stuff in math, please use our google custom search here. Divisibility proofs by induction. Step 3: Show it is true for n=k+1. Step 2 : Let us assume that P(n) is true for some natural number n = k. 10 years ago. 6k+1+4=6×6k+4=6(5M–4)+46k=5M–4by Step 2=30M–20=5(6M−4),which is divisible by 5 Therefore it is true for n=k+1 assuming that it is true for n=k. Step 1:  Show it is true for $$n=0$$.$$6^0 + 4 = 5$$, which is divisible by $$5$$Step 2:  Assume that it is true for $$n=k$$.That is, $$6^k + 4 = 5M$$, where $$M \in I$$.Step 3:  Show it is true for $$n=k+1$$.That is, $$6^{k+1} + 4 = 5P$$, where $$P \in I$$.\begin{aligned} \displaystyle \require{color}6^{k+1} + 4 &= 6 \times 6^k +4 \\&= 6 (5M – 4) + 4 \ \ \ \color{red} 6^k = 5M – 4 \ \ \ \ \text{ by Step 2} \\&= 30M – 20 \\&= 5(6M-4), \text{ which is divisible by 5} \\\end{aligned}Therefore it is true for $$n=k+1$$ assuming that it is true for $$n=k$$.Therefore $$6^n + 4$$ is always divisible by $$5$$.