Let the equation of the tangent at the required point be:Originally Posted byKiwigirl

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We need to find the slope of the tangent, which is , and

to find this we need to use the result that:

So at the slope of the tangent is .

So now we know that the equation of the tangent is of the form:

,

and that at , and , so the tangent passes through the point

, .

Hence:

,

so:

,

and the equation of the tangent is:

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RonL