MHB Derivative of Integral: Does the $x^2$ Cancel?

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The discussion centers on applying the Leibniz Integral Rule to evaluate the derivative of an integral with variable limits. The integral in question is $$\frac{d}{dx}\int_{x^2}^{10}\frac{dz}{z^2+1}$$, where the upper limit is a constant and the lower limit is a function of x. Participants clarify that the derivative of the integral involves evaluating the function at the limits and multiplying by the derivatives of those limits. The final result is derived as $$-\frac{2x}{x^4+1}$$, confirming that the $x^2$ does not cancel out but rather contributes to the derivative's calculation. The conversation highlights the importance of understanding variable limits in integral calculus.
karush
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I assume the derivative cancels the intregal but the $x^2$ ?
 
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The Leibniz Integral Rule states:

$$\frac{d}{dx}\int_{g(x)}^{h(x)}f(t)\,dt=f(h(x))h'(x)-f(g(x))g'(x)$$

Can you proceed?
 
$h\left(x\right)=10h'\implies\left(x\right)=0$
$g\left(x\right)={x}^{2} \implies g'\left(x\right)=2x$
$f\left(z\right)=\frac{1}{{z}^{2}}+1$

I think that is $x^2$ it a fuzzy pic

I have to submit to preview the site freezes up if I preview on the edit page
 
Last edited:
The image is hard to read, but it appear to be that we are asked to evaluate:

$$\frac{d}{dx}\int_{x^3}^{10}\frac{dz}{z^2+1}$$

And if this is the case, then we have:

$$g(x)=x^3\implies g'(x)=3x^2$$

$$h(x)=10\implies h'(x)=0$$

$$f(z)=\frac{1}{z^2+1}$$
 
The original pic looks like $x^2$

So I got
$\frac{2x}{{x}^{4}+1}$

I hope
 
Last edited:
If the lower limit is $x^2$, then we have:

$$\frac{d}{dx}\int_{x^2}^{10}\frac{dz}{z^2+1}=\frac{1}{10^2+1}\cdot0-\frac{1}{(x^2)^2+1}\cdot2x=-\frac{2x}{x^4+1}$$
 
Cool, always learn a lot from MHB
 

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