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Finding k Values for Tangency of y=kx-2 and f(x) = x^2

Thread starter Carl_M
Start date Feb 9, 2010

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Carl_M

Thread starter
Feb 9, 2010

#1

Homework Statement

For what values of k is the line y = kx - 2 tangent to the graph of f(x) = x^2?

Homework Equations

The Attempt at a Solution

Would I just find f'(x) = 2x?

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Discussion

rock.freak667

Homework Helper

Feb 9, 2010

#2

Carl_M said:

The Attempt at a Solution

Would I just find f'(x) = 2x?

No but solving y=kx-2 and y=x² would yield only one solution for x

Hint: recall the condition in the quadratic equation formula for equal roots.

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