#### bumblebee123

##### Junior Member

- Joined
- Jan 3, 2018

- Messages
- 200

**question:**for a curve

**dy/dx**= 3x^2 + 75 Determine how many turning points the curve has

I thought that the turning points would be when the gradient = 0, so 0 = 3x^2 + 75 this means, to solve for x, 3( x^2 + 25 ) however this would give me x = sqrt -25

but negative numbers cannot be square rooted. This means x = 0.

the answer says that it has 0 turning points. Why is this?

any help would be really appreciated