stewartlindsay
Nov 24, 2009, 01:18 PM
Find the gradient of the tangent to the curve y= square root x plus 8/square root x at the point (4,6)
galactus
Nov 24, 2009, 01:26 PM
y=\sqrt{x}+\frac{8}{\sqrt{x}}
Please use proper grouping so we know what you mean. I knew this by plugging in x=4 and seeing if I got 6.
To find the gradient, we need the slope at that point.
Find the derivative of y, then plug in x=4. That should be the slope at that point.
Can you find the derivative of y?
The derivative may be easier to find by rewriting as
x^{\frac{1}{2}}+8x^{\frac{-1}{2}}