beautypg.com

3 constructed functions – Texas Instruments TI-85 User Manual

Page 16

background image

B-16

TI-85/TI-86 Graphing Calculators

Copyright © Houghton Mifflin Company. All rights reserved.

To graphically find an x-intercept, i.e., a value of x at
which the graph crosses the horizontal axis, first press

EXIT

to return the menu to the bottom of the screen.

TI-85

Press

F1

(

MATH

)

F3

(

ROOT

)

TI-86

Press

F1

(

MATH

)

F1

(

ROOT

)

Both

Use

to move the trace cursor near the first

x-intercept, and press

ENTER

.

To find the second x-intercept, press

EXIT

and the

F

-key under

ROOT

, use

to move the trace cursor

near the other x-intercept, and press

ENTER

.

&

1.3 Constructed Functions

Your calculator can find output values of and graph combinations of functions in the same
way that you do these things for a single function. The only additional information you need
is how to enter constructed functions in the graphing list. Suppose that a function f(x) has
been entered in

y

1

and a function g(x) has been entered in

y

2

.

¥ Enter

y

1

+

y

2

in

y

3

to obtain the sum function (f+g)(x) = f(x) + g(x).

¥ Enter

y

1

Ð

y

2

in

y

4

to obtain the sum function (fÐg)(x) = f(x) Ðg(x).

¥ Enter

y

1

*

y

2

in

y

5

to obtain the product function (f.g)(x) = f(x) * g(x).

¥ Enter

y

1

/

y

2

in

y

6

to obtain the quotient function (f

¸g)(x) =

f x

g x

( )

( )

.