Help evaluating integral

[kevin3g]

Say I already know the antiderivative, F(x), and want to find the area between 2 and 3. Is there a way to do F(2)-F(3) without plugging in the function twice?

[toshk]

   

[parisse]

preval

[Wes Loewer]

(03-31-2019 06:48 PM)parisse Wrote:  preval

The 50g had a PREVAL and I figured it meant PR EVALuate, but I always wondered what the "PR" stood for. Is it a French abbreviation?

[parisse]

pr stands for primitive, the French word for antiderivative.

[Wes Loewer]

I learned something new today. I see that the English language https://en.wikipedia.org/wiki/Antiderivative mentions "primitive function" as well. I don't recall ever hearing this term before. Anybody know of any English language countries that use this term?

[dae]

Be sure to purge(x) before using preval(F(x),a,b).

If x has been assigned a value, F(x) will be evaluated using the current x value, before calculating F(b) - F(a).

preval(x^2+x, 2, 3)
outputs 6
only if x has not been assigned a value

Similarly:
f(x) := x^2+x
preval(f(x), 2, 3)
outputs 6
only if x has not been assigned a value

If for instance, x has the value 1, preval(f(x),2,3) will output 0.

Fortunately, if x is purged, then f(x) will revert to the symbolic expression without having to be re-entered.

[Aries]

(03-31-2019 02:16 PM)kevin3g Wrote:  Say I already know the antiderivative, F(x), and want to find the area between 2 and 3. Is there a way to do F(2)-F(3) without plugging in the function twice?

Ehm … you're talking about the first FTC ?
Best,

Aries