Calculus Examples

$f (x) = 1 - x^{2}$ , $(1, 0)$

Step 1

Find the first derivative and evaluate at $x = 1$ and $y = 0$ to find the slope of the tangent line.

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Step 1.1

Differentiate.

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Step 1.1.1

By the Sum Rule, the derivative of $1 - x^{2}$ with respect to $x$ is $\frac{d}{d x} [1] + \frac{d}{d x} [- x^{2}]$ .

$\frac{d}{d x} [1] + \frac{d}{d x} [- x^{2}]$

Step 1.1.2

Since $1$ is constant with respect to $x$ , the derivative of $1$ with respect to $x$ is $0$ .

$0 + \frac{d}{d x} [- x^{2}]$

Step 1.2

Evaluate $\frac{d}{d x} [- x^{2}]$ .

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Step 1.2.1

Since $- 1$ is constant with respect to $x$ , the derivative of $- x^{2}$ with respect to $x$ is $- \frac{d}{d x} [x^{2}]$ .

$0 - \frac{d}{d x} [x^{2}]$

Step 1.2.2

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$0 - (2 x)$

Step 1.2.3

Multiply $2$ by $- 1$ .

$0 - 2 x$

Step 1.3

Subtract $2 x$ from $0$ .

$- 2 x$

Step 1.4

Evaluate the derivative at $x = 1$ .

$- 2 \cdot 1$

Step 1.5

Multiply $- 2$ by $1$ .

$- 2$

Step 2

Plug the slope and point values into the point-slope formula and solve for $y$ .

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Step 2.1

Use the slope $- 2$ and a given point $(1, 0)$ to substitute for $x_{1}$ and $y_{1}$ in the point-slope form $y - y_{1} = m (x - x_{1})$ , which is derived from the slope equation $m = \frac{y_{2} - y_{1}}{x_{2} - x_{1}}$ .

$y - (0) = - 2 \cdot (x - (1))$

Step 2.2

Simplify the equation and keep it in point-slope form.

$y + 0 = - 2 \cdot (x - 1)$

Step 2.3

Solve for $y$ .

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Step 2.3.1

Add $y$ and $0$ .

$y = - 2 \cdot (x - 1)$

Step 2.3.2

Simplify $- 2 \cdot (x - 1)$ .

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Step 2.3.2.1

Apply the distributive property.

$y = - 2 x - 2 \cdot - 1$

Step 2.3.2.2

Multiply $- 2$ by $- 1$ .

$y = - 2 x + 2$

Step 3