Let us assume
I = \(\int\limits_{0}^{5}\cfrac{\sqrt[4]{\text x+4}}{\sqrt[4]{\text x+4}+\sqrt [4]{9-\text x}}d\text x \)... equation 1
By property we know that
I = \(\int\limits_{0}^{5}\cfrac{\sqrt[4]{9-\text x}}{\sqrt[4]{9-\text x}+\sqrt [4]{\text x+4}}d\text x \)...equation 2
Adding equation 1 and 2
2I = \(\int\limits_{0}^{5}\cfrac{\sqrt[4]{\text x+4}}{\sqrt[4]{\text x+4}+\sqrt [4]{9-\text x}}d\text x \) + \(\int\limits_{0}^{5}\cfrac{\sqrt[4]{9-\text x}}{\sqrt[4]{9-\text x}+\sqrt [4]{\text x+4}}d\text x \)
We know