Undefined Equations Involving Infinity

I find it interesting that to this day, not all equations involving infinity can be defined. Is this because the answers have yet to be discovered? Or, is there simply no solution? Wikipedia states that the following equations involving infinity are undefined:

+/- infinity multiplied by 0 = undefined

infinity multiplied by negative infinity = undefined

+/- infinity dividided by +/- infinity = undefined

1 to the power of +/- infinity = undefined