Chapter 2 - Solving Equations - 2-7 Solving Proportions - Practice and Problem-Solving Exercises - Page 129: 57

x=$-\frac{5}{7}$

$\frac{5x}{x^{3}+5}=\frac{5}{x^{2}-7}$ Expand: $5x^3-35x=5x^3+25$ Subtract $5x^3$ from both sides: $5x^{3}-35x-5x^{3}=5x^{3}+25-5x^3$ Simplify: $-35x=25$ Divide both sides by -35: $\frac{-35x}{-35}=\frac{25}{-35}$ Simplify: $x=-\frac{5}{7}$