Prove that the curves y2 = 4x and x2 + y2 – 6x + 1 = 0 touch each other at the point (1, 2).
Given: two curves y2 = 4x and x2 + y2 – 6x + 1 = 0
To prove: the two curves touch each other at point (1,2)
Explanation:
Now given x2 + y2 – 6x + 1 = 0
Differentiating this with respect to x, we get
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Applying sum rule of differentiation, we get
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Solving the above equation at point (1,2), we get

Also given y2 = 4x
Differentiating this with respect to x, we get
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Now applying the product rule of differentiation, we get
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Solving the above equation at point (1,2), we get

From equation (i) and (ii),
∴ m1 = m2
Therefore, both curves touch each other at point (1,2).
Hence proved