Find the values of the constant m for which the line y = mx is a tangent to the curve y = 2x^2 - 4x + 8.
Solution
To find the values of m for which the line y = mx is a tangent to the curve y = 2x^2 - 4x + 8, we equate the two equations:
\(mx = 2x^2 - 4x + 8\)
Rearrange to form a quadratic equation:
\(2x^2 - (4 + m)x + 8 = 0\)
For the line to be a tangent, the discriminant of this quadratic must be zero:
\(b^2 - 4ac = 0\)
Here, \(a = 2\), \(b = -(4 + m)\), \(c = 8\).
Substitute into the discriminant formula:
\((-(4 + m))^2 - 4 \times 2 \times 8 = 0\)
\((4 + m)^2 - 64 = 0\)
\((4 + m)^2 = 64\)
Take the square root of both sides:
\(4 + m = 8\) or \(4 + m = -8\)
Solve for \(m\):
\(m = 4\) or \(m = -12\)
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