Originally Posted by

**Paymemoney** Hi

I few question i am having troubling finding the gradient:

1) Given that the curve y=ax^2+\frac{b}{x} has a gradient of -5 at the point (2, -2) find the value of a and b.

this is how i approached it:

$\displaystyle \frac{dy}{dx}=2ax+bx^-2$

when x=2

$\displaystyle \frac{dy}{dx}= 4a-\frac{b}{4}=-5 $(1)

when x=2,y=-2

$\displaystyle \frac{dy}{dx}= 4a-\frac{b}{4}=-2 $(2)

(1)-(2)

this is where a got stuck because when i added and minus it didn't work.

2)Find the gradient of the curve $\displaystyle y=\frac{2x-4}{x^2}$ at the point where the curve crosses the x-axis.

P.S