3. Consider in R² the straight line l of equation y = 2.x +1 and the point P= (1, –-1). (a) Use the method of Lagrange multipliers to find the closest point Q to P that lies on the line l. (b) Give a...

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Extracted text: 3. Consider in R² the straight line l of equation y = 2.x +1 and the point P= (1, –-1). (a) Use the method of Lagrange multipliers to find the closest point Q to P that lies on the line l. (b) Give a geometric interpretation of the point Q.