The first one holds iff there is an s.t., while the second one holds iff there is an s.t. . is equivalent to being a quadratic residue, while is equivalent to being a quadratic residue, which is equivalent to being a quadratic residue, and we're done.
Ang unang isa ay mayroong iff may st, Samantalang ang ikalawang isa humahawak iff may st . ay katumbas ng pagiging isang parisukat nalalabi, Habang ay katumbas ng pagiging isang parisukat nalalabi, na kung saan ay katumbas ng pagiging isang parisukat nalalabi, at kami ay tapos na.