Skip to content
Question of 175

Q.Find the derivative of xn+axn−1+a2xn−2+…+an−1x+anx^n + a x^{n-1} + a^2 x^{n-2} + \ldots + a^{n-1} x + a^n for some fixed real number aa.

Rajasthan RbseRajasthan Board Senior Secondary Part-I Examination 2017Subjective· 3mImportance★★★★★
0% · 0/175 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 →

Differentiating term by term (each term akxn−ka^k x^{n-k} gives (n−k)akxn−k−1(n-k)a^k x^{n-k-1}, and the constant ana^n vanishes) gives nxn−1+(n−1)axn−2+⋯+an−1nx^{n-1}+(n-1)ax^{n-2}+\cdots+a^{n-1}.

Let:

y=xn+axn−1+a2xn−2+⋯+an−1x+any = x^n + ax^{n-1} + a^2x^{n-2} + \cdots + a^{n-1}x + a^n

Since aa is a fixed real number, each term akxn−ka^k x^{n-k} (for k=0,1,…,nk=0,1,\ldots,n) differentiates using the power rule, treating aka^k as a constant coefficient:

ddx(akxn−k)=ak(n−k)xn−k−1\frac{d}{dx}\left(a^k x^{n-k}\right) = a^k (n-k)x^{n-k-1}

…

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.