\(-3-5x^2=8x^2-3\)

Add \(5x^2\) to both sides: \(-3 = 13x^2 - 3\)

Add 3 to both sides: \(0 = 13x^2\)

Divide both sides by 13: \(0 = x^2\)

Take the square roots of both sides: \(x = \color{brown}\boxed{0}\)