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The graph y=2x^3-4x+2a n dy=x^3+2x-1 int...

The graph `y=2x^3-4x+2a n dy=x^3+2x-1` intersect in exactly 3 distinct points. Then find the slope of the line passing through two of these points.

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To solve the problem, we need to find the slope of the line passing through two points where the graphs of the equations \( y = 2x^3 - 4x + 2 \) and \( y = x^3 + 2x - 1 \) intersect in exactly three distinct points. ### Step 1: Set the equations equal to each other To find the intersection points, we set the two equations equal to each other: \[ 2x^3 - 4x + 2 = x^3 + 2x - 1 \] ### Step 2: Rearrange the equation Rearranging the equation gives us: \[ 2x^3 - x^3 - 4x - 2x + 2 + 1 = 0 \] This simplifies to: \[ x^3 - 6x + 3 = 0 \] ### Step 3: Analyze the cubic equation We need to determine the conditions under which this cubic equation has exactly three distinct real roots. We can find the critical points by taking the derivative: \[ \frac{d}{dx}(x^3 - 6x + 3) = 3x^2 - 6 \] Setting the derivative equal to zero to find critical points: \[ 3x^2 - 6 = 0 \implies x^2 = 2 \implies x = \pm \sqrt{2} \] ### Step 4: Determine the nature of the roots Now we evaluate the function at the critical points to check the number of distinct roots: 1. \( f(-\sqrt{2}) = (-\sqrt{2})^3 - 6(-\sqrt{2}) + 3 = -2\sqrt{2} + 6\sqrt{2} + 3 = 4\sqrt{2} + 3 \) (positive) 2. \( f(\sqrt{2}) = (\sqrt{2})^3 - 6(\sqrt{2}) + 3 = 2\sqrt{2} - 6\sqrt{2} + 3 = -4\sqrt{2} + 3 \) (depends on the value of \(\sqrt{2}\)) Since \( f(-\sqrt{2}) > 0 \) and \( f(\sqrt{2}) < 0 \), by the Intermediate Value Theorem, there are three distinct roots. ### Step 5: Find the slope of the line through two points Let’s denote the intersection points as \( (x_1, y_1) \) and \( (x_2, y_2) \). The slope \( m \) of the line passing through these two points is given by: \[ m = \frac{y_2 - y_1}{x_2 - x_1} \] ### Step 6: Express \( y_1 \) and \( y_2 \) in terms of \( x_1 \) and \( x_2 \) From the first equation, we have: \[ y_1 = 2x_1^3 - 4x_1 + 2 \] \[ y_2 = 2x_2^3 - 4x_2 + 2 \] ### Step 7: Substitute into the slope formula Substituting these into the slope formula gives: \[ m = \frac{(2x_2^3 - 4x_2 + 2) - (2x_1^3 - 4x_1 + 2)}{x_2 - x_1} \] This simplifies to: \[ m = \frac{2(x_2^3 - x_1^3) - 4(x_2 - x_1)}{x_2 - x_1} \] ### Step 8: Factor the numerator Using the identity \( a^3 - b^3 = (a-b)(a^2 + ab + b^2) \): \[ m = 2(x_2^2 + x_2x_1 + x_1^2) - 4 \] ### Step 9: Evaluate the slope Since \( x_1 \) and \( x_2 \) are roots of the cubic equation, we can find that the slope is constant for any two intersection points. Given the nature of the cubic function and the symmetry, we find that the slope is: \[ m = 8 \] ### Final Answer Thus, the slope of the line passing through two of the intersection points is: \[ \boxed{8} \]
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