I am not sure if is this has already been discussed here, but I reckon there's a mistake in the solution to 1C-4d. We are asked to find the equation for the tangent line for f(x) = 1/sqrt(x) at x=a. In the solution it is given:
y = (-1/2)*a^(3/2)*(x-a) + 1/sqrt(a)
= -a^(-3/2)*x + (3/2)*a^(-1/2)
First, there's a minus missing in the power of a in the first line. Second, there should be a (1/2) coefficient in front of x in the second line.

The correct tangent line equation should look like:
y = (-1/2)*a^(-3/2)*(x-a) + 1/sqrt(a)
= -(1/2)*a^(-3/2)*x + (3/2)*a^(-1/2)

Question

I am not sure if is this has already been discussed here, but I reckon there's a mistake in the solution to 1C-4d. We are asked to find the equation for the tangent line for f(x) = 1/sqrt(x) at x=a. In the solution it is given: 
y = (-1/2)*a^(3/2)*(x-a) + 1/sqrt(a)
   = -a^(-3/2)*x + (3/2)*a^(-1/2)
First, there's a minus missing in the power of a in the first line. Second, there should be a (1/2) coefficient in front of x in the second line.

The correct tangent line equation should look like:
y = (-1/2)*a^(-3/2)*(x-a) + 1/sqrt(a) 
   = -(1/2)*a^(-3/2)*x + (3/2)*a^(-1/2)