# How do I find the domain of f(x)=5x^2+2x-1?

The domain is all real numbers. $D : \left\{x : \left(x = R\right)\right\} :$
Domain is the set of all possible x values for a function. The function $y = 5 {x}^{2} + 2 x - 1$ is a parabola graphed below:
The function stretches infinitely in both x-directions and is uninterrupted. The y-values (range) are restricted to all values greater than $- 1.2$