Find the slope m of the tangent to the curve
y = 3/√ x at the point where x = a > 0
y = 2x^(-1/2)
dy/dx = -x^(-3/2)
so for x = a , a>0
dy/dx = -1/(√a)^3
good math, bad reading. :-(
Oh well, 2 or 3 , close enough.
blame it on "oldsheimers"