The derivative \(\mathrm{f}^{\prime}(x)\) gives the tangent gradient where the curve is differentiable.
\(\dfrac{\mathrm{d}y}{\mathrm{d}x}=\mathrm{f}^{\prime}(x)\qquad\dfrac{\mathrm{d}}{\mathrm{d}x}(x^n)=nx^{n-1}\)
Apply the power rule where the function and derivative exist. Rewrite roots and reciprocals as powers first.
For a straight line, the gradient is \(\dfrac{y_2-y_1}{x_2-x_1}\): vertical change divided by horizontal change.
Example
For \(y=3\), the gradient is \(0\). For both \(y=2x\) and \(y=2x-3\), the gradient is \(2\).
For \(y=x^2\), the gradient depends on the point on the curve.
\(\dfrac{\mathrm{d}y}{\mathrm{d}x}\)\({}=2x\)
At \(x=-1,0,1,2\), the gradients are respectively \(-2,0,2,4\). At \(x=a\), the gradient is \(2a\).
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