Answer:
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Step-by-step explanation:
Remember that the derivative tells us the slope of the tangent line at a given point.
So, we want to find the equation of the tangent line to f(x) at x=8.
We are given that f'(8) is -10.
In other words, the slope of the tangent line to f(x) at x=8 is -10.
We also know that f(8)=9. In other words, we have the point (8,9).
So, we can use the point-slope form to figure out the equation:
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Substitute -10 for m and let (8,9) be (x₁, y₁). So:

Distribute the -10:
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Add 9 to both sides:
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And we're done!