Get Answers to all your Questions

header-bg qa

Need Solution for R.D.Sharma Maths Class 12 Chapter 18 Indefinite Integrals Exercise 18.20 Question 8 Maths Textbook Solution.

Answers (1)

Answer: \frac{x^{2}}{2}+2 x+\frac{3}{2} \log \left|x^{2}-x+1\right|+\frac{1}{\sqrt{3}} \tan ^{-1}\left(\frac{2 x-1}{\sqrt{3}}\right)+c

Given: \int \frac{x^{3}+x^{2}+2 x+1}{x^{2}-x+1} d x

Hint: Useing \int \frac{1}{x} d x \text { and } \int \frac{1}{1+x^{2}} d x


            I=\int \frac{x^{3}+x^{2}+2 x+1}{x^{2}-x+1} d x

\frac{x^{3}+x^{2}+2 x+1}{x^{2}-x+1}=(x+2)+\left(\frac{3 x-1}{x^{2}-x+1}\right)

       \therefore \int \frac{x^{3}+x^{2}+2 x+1}{x^{2}-2 x+1} d x=\int(x+2) d x+\frac{3}{2} \int \frac{2 x-\frac{2}{3}}{x^{2}-x+1} d x

                                                        =\int(x+2) d x+\frac{3}{2} \int \frac{2 x-1+1-\frac{2}{3}}{x^{2}-x+1} d x

                                                        =\int(x+2) d x+\frac{3}{2} \int \frac{2 x-1}{x^{2}-x+1} d x+\frac{3}{2} \times \frac{1}{3} \int \frac{1}{x^{2}-x+\left(\frac{1}{2}\right)^{2}-\left(\frac{1}{2}\right)^{2}+1} d x

                                                        =\int(x+2) d x+\frac{3}{2} \int \frac{2 x-1}{x^{2}-x+1} d x+\frac{1}{2} \int \frac{1}{\left(x-\frac{1}{2}\right)^{2}+\left(\frac{\sqrt{3}}{2}\right)^{2}} d x

                                                         =\frac{x^{2}}{2}+2 x+\frac{3}{2} \log \left|x^{2}-x+1\right|+\frac{1}{2} \times \frac{1}{\frac{\sqrt{3}}{2}} \tan ^{-1}\left(\frac{2 x-1}{\sqrt{3}}\right)+c

                                                        =\frac{x^{2}}{2}+2 x+\frac{3}{2} \log \left|x^{2}-x+1\right|+\frac{1}{\sqrt{3}} \tan ^{-1}\left(\frac{2 x-1}{\sqrt{3}}\right)+c


Posted by


View full answer

Crack CUET with india's "Best Teachers"

  • HD Video Lectures
  • Unlimited Mock Tests
  • Faculty Support