To evaluate the expression `(2t+4)^4 / r^2` for `r=-2` and `t=-4`, we first need to substitute these values into the expression:
`(2t+4)^4 / r^2 = (2(-4)+4)^4 / (-2)^2`
Simplifying the numerator:
`= (2(-4) + 4)^4 / (-2)^2`
`= (8)^4 / 4`
`= 4096 / 4`
`= 1024`
Therefore, the value of the expression `(2t+4)^4 / r^2` for `r=-2` and `t=-4` is `1024`.