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 ..

# Cp Doen't Solve This Simple Equation.

Started by
Serj
, Jun 13 2007 01:31 PM

6 replies to this topic

### #1

Posted 13 June 2007 - 01:31 PM

### #2

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

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

### #3

Posted 13 June 2007 - 01:49 PM

I found nothing wrong...

(CPM OS 3.0)

(CPM OS 3.0)

### #4

Posted 13 June 2007 - 02:14 PM

Thanks for the reply.

Doing it that way also gives me the right answer.. but doing exactly solve(0.5 * 1E-4 * 32 * (x-0.7)^2 -4E-4 = 0, x)

it still gives the error. Vanhoa, it this normal?

Doing it that way also gives me the right answer.. but doing exactly solve(0.5 * 1E-4 * 32 * (x-0.7)^2 -4E-4 = 0, x)

it still gives the error. Vanhoa, it this normal?

### #5

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 ...

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 ...

### #6

Posted 13 June 2007 - 03:59 PM

Let's take a look:

(CPM OS 3.0)

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

But:

=> if

(Only on OS 3!)

(CPM OS 3.0)

**This is calculated in both***decimal***and***standard***mode:**

solve( a * ( x - b ) ^ 2 = c )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 inThis 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!)

### #7

Posted 13 June 2007 - 09:01 PM

Damn Vanhoa.. you really must have a programmers brain because you decomposed that to see where the algorithm was wrong. It is the most straight forward one, but maybe it makes an error while rewriting that equation. Anyway one more for the bug list.

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