# How do you know a function is decreasing or increasing at #x=1# given the function #4x^2-9x#?

##### 1 Answer

Usually what people mean when they ask this question is "Is the slope of the tangent line at

For

Whether we think of the derivative as the slope of the tangent line or the rate of change, it is clear that when

This is generally explained by saying that,

at

(There is a bit of a conflict in terminology here. A function is constant at a single value of