HP 38g Graphing Calculator User Manual

Page 47

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Indeflnite

Integrals

You can mix formal names and real variables. Evaluating

(A*s2) ^ will substitute a number for

but not for

s2.

If you want to evaluate an expression like (sl*s2) ^

numerically, you can do so using the I

(where}

command,

listed in the MATH menu under the Symbolic category. For

instance, if you wanted

si = 3

and

s2 =

4, you would enter

(sl*s2)

''2

I (sl=3, s2=4). (The = symbol is in the CHARS

menu: press ■ [CHARS] {{OK}}).

To find the indefinite integral (with a symbolic rather than

numeric result), use formal variables (that is, sO through s5)

for a limit of integration. For instance, to compute

(6x - 5)dx

ehter the integration as / (0, si, 6*x'-5, X).

0 and si are the lower and upper limits, and X is the variable

of integration.

Definite
Integrals

Derivatives

1. Enter the the integration expression in the Home edit line.

(The

symbol in the the CHARS menu.)

2. Press [ENTER], which produces an intermediate result.

3. Press 0 ([COPY]} [ENTER] to complete the evaluation.

The result of /(0,sl,6*X2-5,X) should be

-(5*sl)+6*(s 1^3/3), that is, 2x3-5x.Translators: in Comma

mode; change syntax to use periods.

To find the definite integral (with a numeric result), use

numeric values (numbers or real variables containing

numbers) for both the upper and lower limits. For instance, if

you enter J(-2,3,6*X2-5,X)and press [ENTER] , the result is

45.

To find the symbolic derivative of an expression, use a formal

variable (s 1, etc.) to define the derivative. For example, to

find D/6x*-5x), enter 3sl (6*sl^- 5*sl) .The result is

6*(2*sl) -5, which is equal to 12x—5.

If you use real variables or numbers in the derivative, the

calculator will find a numeric result.

Mathematical Calculations 2-11