Mathematics

Mathematics

Problem

Evaluate ∫x2(x3+1)2 dx\displaystyle \int \frac{x^{2}}{(x^{3}+1)^{2}}\,dx.
Intuitive explanation

The key is recognizing that the denominator (x3+1)2(x^3+1)^2 and numerator x2x^2 are intimately connected through substitution. Notice that the derivative of x3+1x^3+1 is 3x23x^2—almost exactly what's in the numerator. By setting u=x3+1u = x^3+1, you'll transform this into a simple power-rule integral, turning a complicated rational function into something you can integrate in one step.

Intuitive explanation

The key is recognizing that the denominator (x3+1)2(x^3+1)^2 and numerator x2x^2 are intimately connected through substitution. Notice that the derivative of x3+1x^3+1 is 3x23x^2—almost exactly what's in the numerator. By setting u=x3+1u = x^3+1, you'll transform this into a simple power-rule integral, turning a complicated rational function into something you can integrate in one step.

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