What does this equation mean?

Hitting the 127-point ceiling says nothing yet about which stats should receive the investment — that answer depends on what the spread is actually for. For the Swords Dance set’s job, sweeping through a metagame’s Speed tiers with a boosted physical attack, I define a proposed measure I will call the sweep index: the product of a Pokémon’s final Attack stat and its final Speed stat. This is not an official in-game statistic; it is this article’s own construct, chosen because a physical sweeper that hits hard but moves last contributes nothing, a sweeper that moves first but hits softly contributes little, and a product (rather than a sum) captures that the two failure modes compound rather than merely add. Writing x for invested Attack EVs and y for invested Speed EVs and relaxing the two internal floors to their continuous approximation for tractability, Garchomp’s Jolly-natured sweep index becomes f(x,y) = (296+x/4)(264+0.275y) , and maximizing it subject to a shared budget x+y=B through a Lagrangian $\mathcal{L}(x,y,\lambda) = (296+\tfrac{x}{4})(264+0.275y) - \lambda(x+y-B)$. produces first-order conditions $\tfrac{1}{4}$(264+0.275y) = $\lambda$ = 0.275\,(296+$\tfrac{x}{4}$) , which reduce, after clearing terms, to a single tangency condition independent of the budget size: