When u differentiate a curve, d differential tells d slope of tangent rite???? wel wat if it is a cubic equation and when we diff. it we get a quadratic, but a quadratic eqn. is not a straight line and it cant be d tangent of it correct?????
eg. y=x3+x2....
dy/dx=3x2+2x...
so this dy/dx cannot be a tangent and so their cant be a slope of it.......This may seem a very stupid doubt but plzzz explain......
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1 Answers
33When we differentiate a curve we get slope of the tangent not the equation of the tangent.
For example:
take y=2x+2
differentiating it we get "2" so 2 is slope of tangent not the equation of tangent.
take y=x2+4x+2
differentiating it we get 2x+4 but this is not the equation of tangent it is slope at any point (x,f(x))
so tangent at any point (x0,x02+4x0+2) is y=(2x0+4)x+c
where c can be found by putting (x0,x02+4x0+2) in equation y=(2x0+4)x+c..
hope its clear...
