Symbolic Definite Integrals

[Sanmeflo]

Good Afternoon to everybody.

I was trying to make a symbolic definite integral on my HP50G but I don't know how to do it.

For example and integral from 0 to y of x^2+3 dx. If I use the integrer symbol it says "ERROR". 

What's the command to make and integral like that?

[Joe_Horn]

Parhaps one of your variables had an assigned value? If so, that can prevent symbolic manipulations from working correctly, since their value gets substituted in. Try again after purging the variables you're using.

In RPN mode, put these on the stack in this order (assuming that X and Y have no value):

0

'Y'

'X^2+3'

'X'

then press the integral key (right-shift TAN).  You should get (Y^3+9Y)/3 as the result.

Or you can use the EquationWriter to enter the integral in textbook format.

Disclaimer: I don't work for HP. I'm just another happy HP calculator user.

[Sanmeflo]

It says ->NUM ERROR: UNDEFINED NAME

[calcpeace]

Hello sanmeflo,

maybe you use your calc with the wrong mode for a symbolic calculation.

Press on your calc MODE then submenu CAS and uncheck "Numeric" and "Approx". Now your calc is in the EXACT mode.

Use the input Joe Horn posted and you will succeed (or better your hp50g will be able to solve your problem).

Sincerely calcpeace 

[Joe_Horn]

In addition to calcpeace's good suggestion, here's another thought. You're getting a ->NUM error, that indicates that you might be pressing the ->NUM key, which means "evaluate all the way down to a NUMber", which is not what you want here. Since you want to evaluate it symbolically, not numerically, only use EVAL (which is a primary key), or SIMPLIFY, or one of the many other commands that simplify algebraic expressions, some of which can be found in the CONVERT / REWRITE menu. However, if you use the integral key in RPN mode as suggested above, the correct symbolic answer will appear immediately without needing to press EVAL or anything else.