Find the derivative of y = 2x2 − x + 3 from first principles.

Given $f(x) = 2x^2 - x + 3$.
Substitute $(x+h)$ into $f(x)$ to find $f(x+h)$:

$$f(x+h) = 2(x+h)^2 - (x+h) + 3$$ $$f(x+h) = 2(x^2 + 2xh + h^2) - x - h + 3$$ $$f(x+h) = 2x^2 + 4xh + 2h^2 - x - h + 3$$

$$f(x+h) - f(x) = (2x^2 + 4xh + 2h^2 - x - h + 3) - (2x^2 - x + 3)$$ $$f(x+h) - f(x) = 2x^2 + 4xh + 2h^2 - x - h + 3 - 2x^2 + x - 3$$ $$f(x+h) - f(x) = 4xh + 2h^2 - h$$

$$f'(x) = \lim_{h \to 0} \frac{h(4x + 2h - 1)}{h}$$

Since $h \to 0$ but $h \neq 0$, we can cancel $h$:

$$f'(x) = \lim_{h \to 0} (4x + 2h - 1)$$

$$f'(x) = 4x + 2(0) - 1$$ $$f'(x) = 4x - 1$$

The derivative of $y = 2x^2 - x + 3$ is $\boxed{4x - 1}$.