Given `f\left(x\right)=\frac{1}{2}\left(3-x\right)^{2},`
what is the value of `f(15)`?
To find the value of `f(15)`, we need to substitute `x = 15` into the function `f(x)`:
`f(15) = 1/2 (3 - 15)^2`
`f(15) = 1/2 (-12)^2`
`f(15) = 1/2 (144)`
`f(15) = 72`
Therefore, the value of `f(15)` is `72`.