6.Find the relative extrema of f(x,y) = x3 - 4xy + 2y2- 1.

5. The tangent line to the curve y = x3 at the point A(1,1) intersects the curve at another point B. Let R be the area of the region bounded by the curve and the tangent line. The tangent line at B intersects the curve at another point C. Let S be the area of the region bounded by the curve and the second tangent line. Find the values of R and S.