Cp Doen't Solve This Simple Equation.

Posted 13 June 2007 - 01:31 PM

I did a solve(0.5 * 1E-4 * 32 * (x-0.7)^2 -4E-4 = 0, x) and it gave me these solutions:
x=0.9 or x=1.9 . Which are completely wrong and really screwed me because this was during an exame, I only have this calc over a month and it's really pissing me off . Any comments?

Oh and I have os 3.1 ..

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Posted 13 June 2007 - 01:41 PM

I discovered something new, if i do the solve( in Standard it gives me a solution that is 6/5, which is 1.2 and is the right solution.

Is this a bug, if so its really stupid, like the not being able to do comples exponentials in degrees. Very bad Casio

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Posted 13 June 2007 - 01:49 PM

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Posted 13 June 2007 - 02:14 PM

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Posted 13 June 2007 - 03:30 PM

Yes... This is not normal.

0.9 and 1.9 are roots of (x-7/5)^2/625-1/2500
but your equation is (x-7/10)^2/625-1/2500

I dont know why 7/10 can be changed to 7/5 ...

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Posted 13 June 2007 - 03:59 PM

Let's take a look:

(CPM OS 3.0)
This is calculated in both decimal and standard mode:

solve( a * ( x - b ) ^ 2 = c )
{x=b-(a*c)^0.5/a,x=b+(a*c)^0.5/a}


And then:
This is calculated in standard mode:

solve( a * ( x - b ) ^ 2 = c | b = 0.1 )
{x=(-(a*c)^0.5)/a+0.1,x=(a*c)^0.5/a+0.1}

This is calculated in decimal mode:

solve( a * ( x - b ) ^ 2 = c | b = 0.1 )
{x=(-(a*c)^0.5)/a+0.2,x=(a*c)^0.5/a+0.2}

But:
This is calculated in standard mode:

solve( a * ( x - b ) ^ 2 = c | b = 1 )
{x=(-(a*c)^0.5)/a+1,x=(a*c)^0.5/a+1}

This is calculated in decimal mode:

solve( a * ( x - b ) ^ 2 = c | b = 1 )
{x=(-(a*c)^0.5)/a+1,x=(a*c)^0.5/a+1}


=> if b is decimal, it is multiplied by 2


(Only on OS 3!)

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Posted 13 June 2007 - 09:01 PM

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