Question 392830
Always helps to graph the polynomial so you know what you're looking at. We have the graph:


{{{graph(300, 300, -10, 10, -10, 10, x^3 + 5x^2 - 7)}}}


The positive real solution appears to be approximately 1, so if you have a TI calculator, use nsolve:


nsolve(x^3 + 5x^2 - 7 = 0, x, 1)


Another way you could solve it using a calculator is via Newton's Method, which uses a recursive sequence to approximate the zero.