1.Show that the parabola y=-x^2 and the line x-4y-18=0 intersect at right angle at one of their points of intersection(於两个交点之一以直角相交) (请问这题方程式如何设) 2.Find the volume of the solid obtained by rotating the region bounded by y=x-x^2 and y=0 about the line x=2 (想请问这题界线是设 0-1 还是 0-2) 3.The plane x+y+z=1 cuts the cylinder x^2+y^2=1 in an ellipse.Use Lagrange multipliers to find the points on the ellipse that lie closest to and farthest from the origin. (这题方程式是 f(x,y,z)=x^2+y^2-1+入(x+y+z-1) 这样设吗 如果方程式求出xyz後要如何求最近最远点 ) 请版友指导 感谢 --

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