An Ellipse from a Combination

Problem

The ellipse x2a2+y2b2=1\dfrac{x^2}{a^2} + \dfrac{y^2}{b^2} = 1 (with a>b>0a > b > 0) has eccentricity 32\dfrac{\sqrt{3}}{2}. The line y=12x+1y = \dfrac{1}{2}x + 1 meets the ellipse at AA and BB, and a point MM on the ellipse satisfies

OM=12OA+32OB.\overrightarrow{OM} = \frac{1}{2}\overrightarrow{OA} + \frac{\sqrt{3}}{2}\overrightarrow{OB}.

Find the equation of the ellipse.

Answer

Solution

Difficulty7/10
TopicsSubstitution, conic sections, analytic geometry, Vieta's Formulas, vectors

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