Condition for Monotonically Decreasing Function

Q. Let $A=\{0,1,2,3,4,5,6,7\}$. Then the number of bijective functions $f:A\to A$ such that $f\left(1\right)+f\left(2\right)=3-f\left(3\right)$ is equal to

Q. $f\left(x\right)=\frac{x}{lo{g}_{e}x},x\ne 1$, is decreasing in interval

1. $(0,e)$
2. $(1,e)$
3. $(e,\infty )$
4. R

Q.

Which of the following is a monotonically decreasing function?

1. f(x) = ln (x)

2. $f\left(x\right)=3-x^3$

3. $f\left(x\right)=e^x$

4. $f\left(x\right)=\frac{1}{x^2}$