5sqrt(x^2) -4 is just x^(5/2) - 4 then you differntitate that and sub in -1 to find the gradient of the tangent at that point. you also gotta find the y value so substitute x into the orginal equation to find y and then use y_1-y=m(x-x_1) to find the equation
Fellas this question
Differentiate that and you will have
Put x=-1 and you will have
There, we have . There is a calculation error from when you subbed in x=-1 and thought you got -1-4=-5. That is why you supposedly got it wrong.