If $\frac{d}{dx}f(x) = 2x + \frac{3}{x}$ and $f(1) = 1$, then $f(x)$ is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → $x^2 + 3 \log |x|$ ##
The given differential equation is
$\frac{d}{dx}f(x) = 2x + \frac{3}{x}$
Integrating both sides:
$\int d[f(x)] = \int \left(2x + \frac{3}{x}\right) dx$
$f(x) = \frac{2x^2}{2} + 3 \log |x| + c$
$f(x) = x^2 + 3 \log |x| + c$
Putting $x = 1, f(1) = 1$ in above equation:
$1 = 1 + 3 \log |1| + c$
$c = 0$
$∴f(x) = x^2 + 3 \log |x|$