$\"\"$ $\"\"$ $\"\"$

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Slope of the two non vertical lines is $\"\"$ .

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Replace $\"\"$ in slope formula.

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$\"\"$

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$\"\"$ (Product of two same signs is positive) $\"\"$

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Apply multiplication property of equality: Multiply each side by ( k+4).

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$\"\"$

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$\"\"$ (Cancel common terms)

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$\"\"$ (Multiply: $\"\"$ ) $\"\"$

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Apply addition property of equality: Add 2k to each side.

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$\"\"$

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Rearrange the terms using commutative property: a + b = b + a.

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$\"\"$

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$\"\"$ (Apply additive inverse property: $\"\"$ )

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$\"\"$ (Apply additive identity property: $\"\"$ )

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$\"\"$ (Add: $\"\"$ ) $\"\"$

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Apply addition property of equality: Add 4 to each side.

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$\"\"$

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$\"\"$ (Apply additive inverse property: $\"\"$ )

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$\"\"$ (Apply additive identity property: $\"\"$ )

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$\"\"$ (Add: $\"\"$ ) $\"\"$

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Check:

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To check the solution, substitute $\"\"$ in $\"\"$ .

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$\"\"$

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$\"\"$ (Product of two same signs is positive)

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$\"\"$ (Add: $\"\"$ )

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$\"\"$ (Cancel common terms)

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Compare the values, the equation is true. $\"\"$

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The value of $\"\"$ .