[lit-ideas] Re: Don't Laugh (Math)

• From: David Ritchie <ritchierd@xxxxxxxxxxxxx>
• To: lit-ideas@xxxxxxxxxxxxx
• Date: Fri, 23 Jun 2006 14:10:25 -0700

Hi Erin,
my dad asked me if I knew how to do this, and coincidentally, we just went over this this year in math class.
How you solve the problem is you first multiply out (x+y)^4, which gives you, if you don't simplify it completely, (x^2+2xy+y^2)(x^2+2xy+y^2). This is the same as the first equation, only multiplied by itself, so to get the answer, you need to multiply the 9 by itself, which gives you 81. I hope this helps.
Julia Ritche

`On Jun 23, 2006, at 12:35 PM, Erin Holder wrote:`

`OK, who can explain to me how to solve this:`

`If     x^2+2xy+y^2 = 9      then   (x+y)^4 = ?`

I know the answer is "81", I just don't know how to get it. It's starting to
frustrate me. I haven't done this stuff in almost ten years, and I can't for
the life of me remember how to go about it (although I seem to be getting the
hang of some of the other ones...?)

```Erin
TO```

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