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# Maths help watch

1. Find equation of tangent and normal of equation
y=2x^2 -4x at (1,-2)
I worked out the gradient of the tangent by doing dy/dx
I substituted 1 so i got 0 as the gradient
y=+c
-2=c
So I GOT Y=-2
I'm stuck on the equation of the normal
it's -1/dereivitive of the equation at x=1, but that equals 1/0?
2. (Original post by mariejuana)
Find equation of tangent and normal of equation
y=2x^2 -4x at (1,-2)
I worked out the gradient of the tangent by doing dy/dx
I substituted 1 so i got 0 as the gradient
y=+c
-2=c
So I GOT Y=-2
I'm stuck on the equation of the normal
it's -1/dereivitive of the equation at x=1, but that equals 1/0?
Ugh what
3. halp
4. Think about it graphically. y=-2 is a horizontal line. The normal to that would be a vertical line (undefined gradient). x = ???.
5. (Original post by Edgemaster)
Think about it graphically. y=-2 is a horizontal line. The normal to that would be a vertical line (undefined gradient). x = ???.
1?
6. (Original post by mariejuana)
1?
Yes.

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