HP 40gs User Manual

Page 213

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Computer Algebra System (CAS)

14-31

Example 3

Typing:

LIN(SIN(X))

gives:

LNCOLLECT

Regroup the logarithms

LNCOLLECT has as an argument an expression
containing logarithms.

LNCOLLECT regroups the terms in the logarithms. It is
therefore preferable to use an expression that has already
been factored (using

FACTOR).

Typing:

LNCOLLECT(LN(X+1)+LN(X-1))

gives:

ln((x+1)(x−1))

POWEXPAND

Transform a power

POWEXPAND writes a power in the form of a product.

Typing:

POWEXPAND((X+1)

3

)

gives:

(x+1) · (x+1) · (x+1)

This allows you to do the development of (x + 1)

3

in step

by step, using

DISTRIB several times on the preceding

result.

SINCOS

Transform the complex exponentials into sin and cos

SINCOS takes as an argument an expression containing
complex exponentials.

SINCOS then rewrites this expression in terms of sin(x)
and cos(x).

1
4

---

2 i x

⋅ ⋅

(

)

(

)

exp

1
2

--- 1

4

---

2 i x

⋅ ⋅

(

)

exp

+ +

i

2

---

i x

exp

i

2

---

i x

(

)

(

)

exp

+

hp40g+.book Page 31 Friday, December 9, 2005 1:03 AM

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