Re: SameQ to check for simplified radical expressions... doesn't work
- To: mathgroup at smc.vnet.net
- Subject: [mg120976] Re: SameQ to check for simplified radical expressions... doesn't work
- From: DrMajorBob <btreat1 at austin.rr.com>
- Date: Sat, 20 Aug 2011 06:15:57 -0400 (EDT)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
Here are your three expressions: {Simplify[Sqrt[360]], Sqrt[360], Hold[6*Sqrt[10]]} {6 Sqrt[10], 6 Sqrt[10], Hold[6 Sqrt[10]]} As you can see, the first two are identical, and the third is not. So the "problem" is that Simplify isn't doing anything. Now consider: FullForm@Sqrt[360] Times[6,Power[10,Rational[1,2]]] Now imagine this one with 360 in place of 10: FullForm@Sqrt[10] Power[10,Rational[1,2]] LeafCount /@ {Sqrt[360], Sqrt[10]} {7, 5} ByteCount /@ {Sqrt[360], Sqrt[10]} {264, 184} The second is obviously simpler, hence Sqrt[360] is simpler than 6 Sqrt[10]. But Mathematica doesn't see it that way, and apparently, neither do you. Bobby On Fri, 19 Aug 2011 05:33:06 -0500, Roy Simpson <roy at mathemaddicts.com> wrote: > Hello, > > I have what appears to be a simple issue, but I cannot for the life of > me figure it out. I will have a randomized number, a, and I am going to > simplify the square root of this. Then I want to compare this to a > radical expression that a student enters, say b. Thus, the idea should > be something like > > Simplify[Sqrt[a]] === Sqrt[b] > > For sake of this example, let's suppose the number I want to consider is > the square root of 360. I only want the statement to return TRUE if the > rhs of this SameQ is exactly 6*Sqrt[10]. > > Unfortunately, > > Simplify[Sqrt[360]] === Sqrt[360] > returns TRUE. > > I tried a few variations with Hold, but they always return false if the > student enters the correct answer. For example, if the student entered > 6*Sqrt[10], then > > Simplify[Sqrt[360]] === Hold[6*Sqrt[10]] > returns FALSE > > What am I doing wrong? Any help would be appreciated. > -- DrMajorBob at yahoo.com
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