Write the set of values of a for which the function `f(x)=a x+b` is decreasing for all `x in R` .

Explanation

`f(x) = ax +b`

`f^{prime}(x)= a+0`

`f^{prime}(x)=a`

for f(x) to be decreasing, it must have

`f^{prime}(x) lt 0`


`therefore a lt o`

`therefore a in (-infty,0)`