Prove by the principle of mathematical induction that 1×1!+2×2!+3×3!+...+n×n!=(n+1)!−1 for all natural numbers n.
Prove by using the principle of mathematical induction ∀n∈N
2+5+8+11+...+(3n−1)=12n(3n+1)
Or
Using principle of mathematical induction, prove that 4n+15n−1is divisible by 9 for all natural numbers n.