Thursday, 3 April 2014

`y = x^(coshx) , (1, 1)` Find an equation of the tangent line to the graph of the function at the given point

Given


`y = x^(coshx) ` , (1, 1) to find the tangent line equation.


let


`y=f(x)`


so,


`f(x) =x^(coshx)`


so let's find `f'(x) = (x^(coshx))'`


on applying the exponent rule we get,


`a^b = e^(b ln(a))`


so ,


`x^(coshx) = e^(coshx lnx)`


so,


`f'(x)= ( e^(coshx lnx))'


`=d/dx ( e^(coshx lnx))`


let `u=coshx ln x`


so ,


`d/dx ( e^(coshx lnx)) = d/ (du) e^u * d/dx (coshx lnx)`


=` e^u * d/dx (coshx lnx)`


...

Given


`y = x^(coshx) ` , (1, 1) to find the tangent line equation.


let


`y=f(x)`


so,


`f(x) =x^(coshx)`


so let's find `f'(x) = (x^(coshx))'`


on applying the exponent rule we get,


`a^b = e^(b ln(a))`


so ,


`x^(coshx) = e^(coshx lnx)`


so,


`f'(x)= ( e^(coshx lnx))'


`=d/dx ( e^(coshx lnx))`


let `u=coshx ln x`


so ,


`d/dx ( e^(coshx lnx)) = d/ (du) e^u * d/dx (coshx lnx)`


=` e^u * d/dx (coshx lnx)`


=`e^u * (sinhx lnx +coshx/x)`


=`e^(coshx ln x) * (sinhx lnx +coshx/x)`


=> `x^coshx * (sinhx lnx +coshx/x)`


now let us find f'(x) value at (1,1) which is slope


f'(1) = `x^cosh(1) (sinh(1) ln(1)+cosh(1)) = x^cosh(1) (0+cosh(1))`


 = `x^cosh(1) (cosh(1))`


now , the slope of the tangent line is` x^cosh(1) (cosh(1))`


we have the solope and the points so the equation of the tangent line is


`y-y1 = slope(x-x1)`


`y-1=slope(x-1)`


`y= slope(x-1) +1`


 =`x^cosh(1) (cosh(1)) (x-1)+1`


but `x^cosh(1) = e^(cosh(1)ln(1)) = e^0 =1`


so,



=`1 (cosh(1)) (x-1)+1`


=` xcoshx -coshx +1`


so ,


`y=xcoshx -coshx +1 ` is the tangent equation

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