The expression: $x^{2}y-x$ contains several variables so we pick x for differentiation

Let's perform the differentiation: $\frac{\mathrm{d}}{\mathrm{d}x}(x^{2}y-x)$

ⓘ The derivative of a sum is the sum of the derivatives: $\frac{\mathrm{d}}{\mathrm{d}x}(x^{2}y-x)$ = $\frac{\mathrm{d}}{\mathrm{d}x}\left(x^{2}y\right)+\frac{\mathrm{d}}{\mathrm{d}x}(-x)$

$\frac{\mathrm{d}}{\mathrm{d}x}\left(x^{2}y\right)+\frac{\mathrm{d}}{\mathrm{d}x}(-x)$

ⓘ For differentiation with respect to $x$, $y$ is treated as constant. A constant factor stays in front of the derivative, (k*u)' = k*u': $\frac{\mathrm{d}}{\mathrm{d}x}\left(x^{2}y\right)$ = $y·\frac{\mathrm{d}}{\mathrm{d}x}\left(x^2\right)$■The derivative of x^n is n*x^(n-1): $\frac{\mathrm{d}}{\mathrm{d}x}\left(x^2\right)$ = $2x$■The derivative of x is 1: $\frac{\mathrm{d}}{\mathrm{d}x}(-x)$ = $-1$

$y·2x-1$

▶Derivative:   $2xy-1$