Tangent Lines

Consider the function f(x)=2x2+3x1f(x) = - 2x^2 + 3x - 1 . There is a point (a,b)(a, b) such that the tangent line to ff at (a,b)(a, b) is perpendicular to the line y=x3+5y = \frac{x}{3} + 5 . Find the point (a,b)(a, b) and write down the equation of the tangent line.
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