Let . of the following expressions equals…

MATHEMATICS · Single correct · CBSE · Mathematics · Integrals · Integrals

Problem

Let I(x)=∫3xx2+1ln⁡(1+t2) dtI(x)=\displaystyle \int_{3x}^{x^{2}+1}\ln\bigl(1+t^{2}\bigr)\,dt. Which of the following expressions equals I′(x)I'(x)? (a) 2x ln⁡(1+(x2+1)2)+3 ln⁡(1+9x2)2x\,\ln\bigl(1+(x^{2}+1)^{2}\bigr)+3\,\ln\bigl(1+9x^{2}\bigr) (b) 4x x2+11+(x2+1)2−18x1+9x24x\,\dfrac{x^{2}+1}{1+(x^{2}+1)^{2}}-\dfrac{18x}{1+9x^{2}} (c) 2x ln⁡(1+(x2+1)2)−3 ln⁡(1+9x2)2x\,\ln\bigl(1+(x^{2}+1)^{2}\bigr)-3\,\ln\bigl(1+9x^{2}\bigr) (d) ln⁡(1+(x2+1)2)−ln⁡(1+9x2)\ln\bigl(1+(x^{2}+1)^{2}\bigr)-\ln\bigl(1+9x^{2}\bigr)

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