The equation of parabola is .

Tangent line to the parabola at is .

Write the tangent line in slope intercept form of line equation..

Comparing above line equation with  we will get slope as

Slope of the tangent line is .

In general, slope of the tangent is derivative of the curve.

Differentiate on each side with respect to .

Find slope at .

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Slope of the tangent line is .

Substitute and in the curve equation.

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Point on the curve is .

Equation of a line at point with slope

Compare the tangent line with , then .

and .