Skip to content
EXERCISE 4.1 · Q6

Q.Prove by method of induction, for all n∈Nn \in N: 1.2+2.3+3.4+…+n(n+1)=n3(n+1)(n+2)1.2 + 2.3 + 3.4 + \ldots + n(n+1) = \dfrac{n}{3}(n+1)(n+2).

Maharashtra MsbshseTextbookSubjectiveImportance★★★★★est
5% · 6/129 Questions
🔒 Locked · start free trial →

You're viewing a preview — the full solution, concept, methods & PYQ mapping are locked.

Start your 14-day free trial to unlock the full solution →

Let P(n):1.2+2.3+⋯+n(n+1)=n3(n+1)(n+2)P(n):1.2+2.3+\cdots+n(n+1)=\dfrac n3(n+1)(n+2). Base: n=1n=1: L.H.S.=2=2, R.H.S.=13(2)(3)=2=\dfrac13(2)(3)=2; holds. Hypothesis: assume true for kk. Step: add (k+1)(k+2)(k+1)(k+2): k3(k+1)(k+2)+(k+1)(k+2)=(k+1)(k+2)[k3+1]=(k+1)(k+2)⋅k+33=(k+1)3(k+2)(k+3)\dfrac k3(k+1)(k+2)+(k+1)(k+2)=(k+1)(k+2)\left[\dfrac k3+1\right]=(k+1)(k+2)\cdot\dfrac{k+3}{3}=\dfrac{(k+1)}{3}(k+2)(k+3), matc …

Unlock everything free for 14 days

  • Full step-by-step solutions
  • Concept-first explanations
  • Methods, shortcuts & mistakes
  • PYQ mapping + timed mock tests

Full access for 14 days. No credit card required.