fx-9860GII      TI-83

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fnInt

On a TI calculator you can calculate the function integral

MATH	9	fnInt(		expression		٬
				variable		٬
				lower		٬
				upper		٬
				toleramce		)		ENTER

or via the CATALOG as

	CATALOG⎵
2nd		0		►fnInt(		ENTER

 

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Explanation

The syntax for using the function integral command is

fnInt( f (x), v, l, u, tol )

where

f (x)	expression
v	variable
l	lower value
u	upper value
tol	tolerance (default = 1E -5)

 

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Example 1

To return the numerical integral for the function

MATH

9

fnInt(

2

X,θ,T,n

x²

+

3

X,θ,T,n

+

4

٬

at start point x = 1 and end point x = 5

1

٬

5

٬

with a tolerance of 1E−4

1

EXP

(–)

4

)

EXE

which gives

fInt(2X²+3X+4,1,5,1E-4) 404┘3

 

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Example 2

To perform the integration calculation for the function

∫dx

π٬٬

π٬٬

≣

cos

X,θ,T,n

٬

SHIFT

EXP

÷

2

٬

SHIFT

EXP

)

EXE

which gives

∫(cos X,π÷2,π) -1

 

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