Irrational numbers. Please help me out with a small algebra problem. I just need someone to explain how this example works. I think I'm just missing something important.

Question

mustap · Answer

And then that equals $$\frac{ 2-6 }{ 2 }$$ which equals -4

mustap · Answer

That's the example. Can someone explain how this was done in the example? I don't understand the first step where xy turns into that crazy equation.

mustap · Answer

Wait I wrote it out wrong my bad

mustap · Answer

Here's the example's first step.
$$xy=\frac{ (x+y)^2-(x^2+y^2) }{ 2 }$$

mustap · Answer

^this right above me, how is xy turned into that number?

mustap · Answer

@jim_thompson5910 could you please help me?

mustap · Answer

Well I got it. Turns out that if you try to solve (x+y)^2−(x2+y2)/2 it turns into xy so I was just being dumb... Thanks for the non help I got anyways!

mustap · Answer

Comment for fun if you want a free medal

directrix · Answer

xy is not turned into that number. But, that algebraic expression simplifies to xy. Hold on.

mustap · Answer

i meant to say simplifies. My bad.

directrix · Answer

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