Solving General Curve y=kx^n Tangent at P(a,kan)

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Homework Statement


Consider now the point P(a, kan) on the general curve y=kxn. where n is any non zero real number and k >0.

find the equation of the tangent at the point P
find coordinates of the points A and B where the tangent meets the x-axis and y-axis respectively.


Homework Equations





The Attempt at a Solution


I have what should be the gradient of the tangent, simply the derivative of y=kxn (dy/dx=knxn-1). but i am unsure as finding the x and y intercepts is proving difficult. Should the highest power of x be 1 as the tangent should be linear, thus making the tangent simply y=kx? or is there something more...
 
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ProgMetal said:

The Attempt at a Solution


I have what should be the gradient of the tangent, simply the derivative of y=kxn (dy/dx=knxn-1). but i am unsure as finding the x and y intercepts is proving difficult. Should the highest power of x be 1 as the tangent should be linear, thus making the tangent simply y=kx? or is there something more...

You would need to get the gradient at point P, which is just dy/dx at x=a. (This will be 'm')

Then just use the formula for find a line given a point and the gradient.

(y-y0)/(x-x0) = m
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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