Find the equation of the tangents to the curve 3x2 – y2 = 8, which passes through the point (4/3, 0).

assume point (a, b) which lies on the given curve


finding the slope of the tangent by differentiating the curve




m(tangent) at (a,b) is


Since this tangent passes through , its slope can also be written as



Equating both the slopes as they are of the same tangent



b2 = 3a2 – 4a …(i)


Since points (a,b) lies on this curve


3a2 – b2 = 8 …(ii)


Solving (i) and (ii) we get


3a2 – 8 = 3a2 – 4a


a = 2


b = 2 or – 2


therefore points are (2,2) or (2, – 2)


equation of tangent is given by y – y1 = m(tangent)(x – x1)


y – 2 = 3(x – 2)


or


y + 2 = – 3(x – 3)


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