NTA Abhyas 2020
- Exam
- NTA Abhyas
- Year
- 2020
- Subject
- Mathematics
- Chapter
- Indefinite Integration
NTA Abhyas 2020 · Mathematics · Indefinite Integration
If the integral ∫ 5 x x - 2 dx = x + a | x - 2 x| + k , then the...
If the integral ∫ \dfrac{5 \text\tan \text{x}}{\text\tan \text{x} - 2} \text{dx} = \text{x} + \text{a} \text\log \left|\text\sin \text{x} - 2 \text\cos \text{x}\right| + \text{k}, then the value of is
Options
- A
- B
- C & & & & &
- D & & & & &
Correct answer
B.
Step-by-step solution
∫ \dfrac{5 \text\tan \text{x}}{\text\tan \text{x} - 2} \text{dx} = \text{x} + \text{a} \text\ln \left|\text\sin \text{x} - 2 \text\cos \text{x}\right| + \text{k}
Differentiating both sides, we get
\dfrac{5 \text\tan \text{x}}{\text\tan \text{x} - 2} = 1 + \dfrac{\text{a} \left(\text\cos \text{x} + 2 \text\sin \text{x}\right)}{\text\sin \text{x} - 2 \text\cos \text{x}}
⇒ \dfrac{5 \text\sin \text{x}}{\text\sin \text{x} - 2 \text\cos \text{x}} = \dfrac{\text\sin \text{x} \left(1 + 2 \text{a}\right) + \text\cos \text{x} \left(\text{a} - 2\right)}{\text\sin \text{x} - 2 \text\cos \text{x}}
Differentiating both sides, we get
\dfrac{5 \text\tan \text{x}}{\text\tan \text{x} - 2} = 1 + \dfrac{\text{a} \left(\text\cos \text{x} + 2 \text\sin \text{x}\right)}{\text\sin \text{x} - 2 \text\cos \text{x}}
⇒ \dfrac{5 \text\sin \text{x}}{\text\sin \text{x} - 2 \text\cos \text{x}} = \dfrac{\text\sin \text{x} \left(1 + 2 \text{a}\right) + \text\cos \text{x} \left(\text{a} - 2\right)}{\text\sin \text{x} - 2 \text\cos \text{x}}