Answer is: option3
\( 2x \sqrt{3 + x^4} \)Solution:
\[ \frac{d}{dx} \int_{a}^{u(x)} f(t) \, dt = f(u(x)) \cdot \frac{du}{dx} \]
Here:
- \( a = 1 \)
- \( u(x) = x^2 \)
- \( f(t) = \sqrt{3 + t^2} \)
So:
\[ \frac{d}{dx} \int_{1}^{x^2} \sqrt{3 + t^2} \, dt = \sqrt{3 + (x^2)^2} \cdot \frac{d}{dx}(x^2) \]
- \( (x^2)^2 = x^4 \)
- \( \frac{d}{dx}(x^2) = 2x \)
So the derivative becomes:
\[ 2x \cdot \sqrt{3 + x^4} \]
Hence option C