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(derivative) Find the equations of the normal lines to the graph of x^2 + 2y^2 = 36 that pass through point (1?

Find the equations of the normal lines to the graph of x^2 + 2y^2 = 36 that pass through point (1,0).

I found one, that is y = 0, but the book says y = 4x - 4 and y = -4x + 4 are answers too. I can't find the other two. How do you solve this question?

THX!

3 Answers

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  • ?
    Lv 4
    10 years ago
    Favorite Answer

    A line through (1, 0) with slope m is given by y = m(x - 1).

    Find where this intersects with the ellipse, for non-zero m.

    The product of m and the slope of the tangent to the ellipse at the point of intersection must be -1. Use this to find possible values of m.

  • ?
    Lv 4
    4 years ago

    Use the formula y = ax + b the place a is the slope... the slope of the given line is -a million/3 and for a perpendicular the slope could desire to be 3 Then it is y = 3x+b ... now use the factor to discover b ... it is 7 = 3*2 + b ==> b =a million Then the equation is y = 3x + a million ok!

  • ?
    Lv 6
    10 years ago

    2x+4ydy/dx=0 dy/dx=-x/2y (1,0) =-1/inf slope is 0

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