Precalculus Examples

Graph x^2-8x-8y-16=0
Step 1
Solve for .
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Step 1.1
Move all terms not containing to the right side of the equation.
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Step 1.1.1
Subtract from both sides of the equation.
Step 1.1.2
Add to both sides of the equation.
Step 1.1.3
Add to both sides of the equation.
Step 1.2
Divide each term in by and simplify.
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Step 1.2.1
Divide each term in by .
Step 1.2.2
Simplify the left side.
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Step 1.2.2.1
Cancel the common factor of .
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Step 1.2.2.1.1
Cancel the common factor.
Step 1.2.2.1.2
Divide by .
Step 1.2.3
Simplify the right side.
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Step 1.2.3.1
Simplify each term.
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Step 1.2.3.1.1
Dividing two negative values results in a positive value.
Step 1.2.3.1.2
Cancel the common factor of and .
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Step 1.2.3.1.2.1
Factor out of .
Step 1.2.3.1.2.2
Move the negative one from the denominator of .
Step 1.2.3.1.3
Rewrite as .
Step 1.2.3.1.4
Divide by .
Step 2
Find the properties of the given parabola.
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Step 2.1
Rewrite the equation in vertex form.
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Step 2.1.1
Complete the square for .
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Step 2.1.1.1
Use the form , to find the values of , , and .
Step 2.1.1.2
Consider the vertex form of a parabola.
Step 2.1.1.3
Find the value of using the formula .
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Step 2.1.1.3.1
Substitute the values of and into the formula .
Step 2.1.1.3.2
Simplify the right side.
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Step 2.1.1.3.2.1
Combine and .
Step 2.1.1.3.2.2
Cancel the common factor of and .
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Step 2.1.1.3.2.2.1
Factor out of .
Step 2.1.1.3.2.2.2
Cancel the common factors.
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Step 2.1.1.3.2.2.2.1
Factor out of .
Step 2.1.1.3.2.2.2.2
Cancel the common factor.
Step 2.1.1.3.2.2.2.3
Rewrite the expression.
Step 2.1.1.3.2.3
Multiply the numerator by the reciprocal of the denominator.
Step 2.1.1.3.2.4
Multiply by .
Step 2.1.1.4
Find the value of using the formula .
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Step 2.1.1.4.1
Substitute the values of , and into the formula .
Step 2.1.1.4.2
Simplify the right side.
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Step 2.1.1.4.2.1
Simplify each term.
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Step 2.1.1.4.2.1.1
Raise to the power of .
Step 2.1.1.4.2.1.2
Combine and .
Step 2.1.1.4.2.1.3
Cancel the common factor of and .
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Step 2.1.1.4.2.1.3.1
Factor out of .
Step 2.1.1.4.2.1.3.2
Cancel the common factors.
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Step 2.1.1.4.2.1.3.2.1
Factor out of .
Step 2.1.1.4.2.1.3.2.2
Cancel the common factor.
Step 2.1.1.4.2.1.3.2.3
Rewrite the expression.
Step 2.1.1.4.2.1.4
Multiply the numerator by the reciprocal of the denominator.
Step 2.1.1.4.2.1.5
Multiply .
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Step 2.1.1.4.2.1.5.1
Multiply by .
Step 2.1.1.4.2.1.5.2
Multiply by .
Step 2.1.1.4.2.2
Subtract from .
Step 2.1.1.5
Substitute the values of , , and into the vertex form .
Step 2.1.2
Set equal to the new right side.
Step 2.2
Use the vertex form, , to determine the values of , , and .
Step 2.3
Since the value of is positive, the parabola opens up.
Opens Up
Step 2.4
Find the vertex .
Step 2.5
Find , the distance from the vertex to the focus.
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Step 2.5.1
Find the distance from the vertex to a focus of the parabola by using the following formula.
Step 2.5.2
Substitute the value of into the formula.
Step 2.5.3
Simplify.
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Step 2.5.3.1
Combine and .
Step 2.5.3.2
Cancel the common factor of and .
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Step 2.5.3.2.1
Factor out of .
Step 2.5.3.2.2
Cancel the common factors.
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Step 2.5.3.2.2.1
Factor out of .
Step 2.5.3.2.2.2
Cancel the common factor.
Step 2.5.3.2.2.3
Rewrite the expression.
Step 2.5.3.3
Multiply the numerator by the reciprocal of the denominator.
Step 2.5.3.4
Multiply by .
Step 2.6
Find the focus.
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Step 2.6.1
The focus of a parabola can be found by adding to the y-coordinate if the parabola opens up or down.
Step 2.6.2
Substitute the known values of , , and into the formula and simplify.
Step 2.7
Find the axis of symmetry by finding the line that passes through the vertex and the focus.
Step 2.8
Find the directrix.
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Step 2.8.1
The directrix of a parabola is the horizontal line found by subtracting from the y-coordinate of the vertex if the parabola opens up or down.
Step 2.8.2
Substitute the known values of and into the formula and simplify.
Step 2.9
Use the properties of the parabola to analyze and graph the parabola.
Direction: Opens Up
Vertex:
Focus:
Axis of Symmetry:
Directrix:
Direction: Opens Up
Vertex:
Focus:
Axis of Symmetry:
Directrix:
Step 3
Select a few values, and plug them into the equation to find the corresponding values. The values should be selected around the vertex.
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Step 3.1
Replace the variable with in the expression.
Step 3.2
Simplify the result.
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Step 3.2.1
Find the common denominator.
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Step 3.2.1.1
Write as a fraction with denominator .
Step 3.2.1.2
Multiply by .
Step 3.2.1.3
Multiply by .
Step 3.2.1.4
Write as a fraction with denominator .
Step 3.2.1.5
Multiply by .
Step 3.2.1.6
Multiply by .
Step 3.2.2
Combine the numerators over the common denominator.
Step 3.2.3
Simplify each term.
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Step 3.2.3.1
Raise to the power of .
Step 3.2.3.2
Multiply .
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Step 3.2.3.2.1
Multiply by .
Step 3.2.3.2.2
Multiply by .
Step 3.2.3.3
Multiply by .
Step 3.2.4
Simplify the expression.
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Step 3.2.4.1
Subtract from .
Step 3.2.4.2
Subtract from .
Step 3.2.4.3
Move the negative in front of the fraction.
Step 3.2.5
The final answer is .
Step 3.3
The value at is .
Step 3.4
Replace the variable with in the expression.
Step 3.5
Simplify the result.
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Step 3.5.1
Find the common denominator.
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Step 3.5.1.1
Write as a fraction with denominator .
Step 3.5.1.2
Multiply by .
Step 3.5.1.3
Multiply by .
Step 3.5.1.4
Write as a fraction with denominator .
Step 3.5.1.5
Multiply by .
Step 3.5.1.6
Multiply by .
Step 3.5.2
Combine the numerators over the common denominator.
Step 3.5.3
Simplify each term.
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Step 3.5.3.1
Raise to the power of .
Step 3.5.3.2
Multiply .
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Step 3.5.3.2.1
Multiply by .
Step 3.5.3.2.2
Multiply by .
Step 3.5.3.3
Multiply by .
Step 3.5.4
Reduce the expression by cancelling the common factors.
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Step 3.5.4.1
Subtract from .
Step 3.5.4.2
Subtract from .
Step 3.5.4.3
Cancel the common factor of and .
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Step 3.5.4.3.1
Factor out of .
Step 3.5.4.3.2
Cancel the common factors.
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Step 3.5.4.3.2.1
Factor out of .
Step 3.5.4.3.2.2
Cancel the common factor.
Step 3.5.4.3.2.3
Rewrite the expression.
Step 3.5.4.4
Move the negative in front of the fraction.
Step 3.5.5
The final answer is .
Step 3.6
The value at is .
Step 3.7
Replace the variable with in the expression.
Step 3.8
Simplify the result.
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Step 3.8.1
Find the common denominator.
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Step 3.8.1.1
Write as a fraction with denominator .
Step 3.8.1.2
Multiply by .
Step 3.8.1.3
Multiply by .
Step 3.8.1.4
Write as a fraction with denominator .
Step 3.8.1.5
Multiply by .
Step 3.8.1.6
Multiply by .
Step 3.8.2
Combine the numerators over the common denominator.
Step 3.8.3
Simplify each term.
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Step 3.8.3.1
Raise to the power of .
Step 3.8.3.2
Multiply .
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Step 3.8.3.2.1
Multiply by .
Step 3.8.3.2.2
Multiply by .
Step 3.8.3.3
Multiply by .
Step 3.8.4
Simplify the expression.
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Step 3.8.4.1
Subtract from .
Step 3.8.4.2
Subtract from .
Step 3.8.4.3
Move the negative in front of the fraction.
Step 3.8.5
The final answer is .
Step 3.9
The value at is .
Step 3.10
Replace the variable with in the expression.
Step 3.11
Simplify the result.
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Step 3.11.1
Find the common denominator.
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Step 3.11.1.1
Write as a fraction with denominator .
Step 3.11.1.2
Multiply by .
Step 3.11.1.3
Multiply by .
Step 3.11.1.4
Write as a fraction with denominator .
Step 3.11.1.5
Multiply by .
Step 3.11.1.6
Multiply by .
Step 3.11.2
Combine the numerators over the common denominator.
Step 3.11.3
Simplify each term.
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Step 3.11.3.1
Raise to the power of .
Step 3.11.3.2
Multiply .
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Step 3.11.3.2.1
Multiply by .
Step 3.11.3.2.2
Multiply by .
Step 3.11.3.3
Multiply by .
Step 3.11.4
Reduce the expression by cancelling the common factors.
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Step 3.11.4.1
Subtract from .
Step 3.11.4.2
Subtract from .
Step 3.11.4.3
Cancel the common factor of and .
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Step 3.11.4.3.1
Factor out of .
Step 3.11.4.3.2
Cancel the common factors.
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Step 3.11.4.3.2.1
Factor out of .
Step 3.11.4.3.2.2
Cancel the common factor.
Step 3.11.4.3.2.3
Rewrite the expression.
Step 3.11.4.4
Move the negative in front of the fraction.
Step 3.11.5
The final answer is .
Step 3.12
The value at is .
Step 3.13
Graph the parabola using its properties and the selected points.
Step 4
Graph the parabola using its properties and the selected points.
Direction: Opens Up
Vertex:
Focus:
Axis of Symmetry:
Directrix:
Step 5