## Calculus: Early Transcendentals 8th Edition

you can see this by subbing it into an equation. lets suppose that f(x) = $x^{2}$ and our value for are variable are s = 2 and t = -2. when we sub this in we get f(2) = 4 f(-2) = 4 however -2 $\ne$ 2 this shows how the y values can be the same with different x values