To find the point of tangency, equate the line and curve equations:
\(kx - k = -\frac{1}{2x}\)
Multiply through by \(2x\) to clear the fraction:
\(2kx^2 - 2kx = -1\)
Rearrange to form a quadratic equation:
\(2kx^2 - 2kx + 1 = 0\)
For the line to be tangent, the discriminant must be zero:
\(b^2 - 4ac = 0\)
Here, \(a = 2k\), \(b = -2k\), \(c = 1\).
\((-2k)^2 - 4(2k)(1) = 0\)
\(4k^2 - 8k = 0\)
Factor out \(4k\):
\(4k(k - 2) = 0\)
Since \(k\) is positive, \(k = 2\).
Substitute \(k = 2\) back into the line equation:
\(y = 2x - 2\)
Equate with the curve equation:
\(2x - 2 = -\frac{1}{2x}\)
Multiply through by \(2x\):
\(4x^2 - 4x + 1 = 0\)
\((2x - 1)^2 = 0\)
\(x = \frac{1}{2}\)
Substitute \(x = \frac{1}{2}\) into the line equation:
\(y = 2 \times \frac{1}{2} - 2 = -1\)
The point of tangency is \(\left( \frac{1}{2}, -1 \right)\).