1. **State the problem:** Simplify the expression $2\sin^2 x + \sin x - \cos^2 x$. 2. **Recall the Pythagorean identity:** $\sin^2 x + \cos^2 x = 1$. 3. **Rewrite $\cos^2 x$ using the identity:** $$\cos^2 x = 1 - \sin^2 x$$ 4. **Substitute into the expression:** $$2\sin^2 x + \sin x - (1 - \sin^2 x)$$ 5. **Simplify inside the parentheses:** $$2\sin^2 x + \sin x - 1 + \sin^2 x$$ 6. **Combine like terms:** $$2\sin^2 x + \sin^2 x + \sin x - 1 = 3\sin^2 x + \sin x - 1$$ 7. **Final simplified expression:** $$3\sin^2 x + \sin x - 1$$ This is the simplified form of the original expression.