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Question

Mathematics Question on Applications of Derivatives

Find the equation of the tangent to the curve which is parallel to the line 4x − 2y + 5 = 0

Answer

The equation of the given curve is y=3x2y=\sqrt{3x-2}.

The slope of the tangent to the given curve at any point (x, y) is given by,

dydx=323x2\frac{dy}{dx}=\frac{3}{2}\sqrt{3x-2}

The equation of the given line is 4x − 2y + 5 = 0

4x − 2y + 5 = 0

∴ y=2x+52\frac{5}{2} (which is of the form y=mx+c)

∴The slope of the line = 2 Now, the tangent to the given curve is parallel to the line 4x − 2y − 5 = 0 if the slope of the tangent is equal to the slope of the line.

323x2\frac{3}{2}\sqrt{3x-2}

3x-2=34\frac{3}{4}

3x-2=916\frac{9}{16}

3x=916\frac{9}{16}+2=4116\frac{41}{16}+2=4116\frac{41}{16}

x=4148\frac{41}{48}

when x=4148\frac{41}{48}, y=3(4148)\sqrt{3(\frac{41}{48})}-2=41162413216\sqrt{\frac{41}{16}}-2\sqrt41-\frac{32}{16}=916\sqrt{\frac{9}{16}}=3/4.

∴The equation of the tangent passing through the point is given by,

=48x-24y=23

Hence, the equation of the required tangent is 48-24y=23.