HP 40gs User Manual page 279

hp40g+.book Page 5 Friday, December 9, 2005 1:03 AM
Example 4
Step-by-Step Examples
Press to select the entire
equation, then press
to reduce it to
2
9x – 6x – 80
.
Press , select
FACTOR, press and
then . The result is
as shown at the right.
Now press , select
SOLVEVX, press and
press . The result is
shown at the right.
Press to display
CAS history, select D or a
version of it, and press
Press , select SUBST,
press and, then
complete the second
x = 5 –
argument:
Press to select
the entire expression and
then to obtain the
intermediate result shown.
Press once more to
175
yield the result: .
D = 175
Therefore, when
x = 5 –
.
A baker produces two assortments of biscuits and
macaroons. A packet of the first assortment contains 17
biscuits and 20 macaroons. A packet of the second
assortment contains 10 biscuits and 25 macaroons. Both
packets cost 90 cents.
Calculate the price of one biscuit, and the price of one
macaroon.
Solution: Let x be the price of one biscuit, and y the
price of one macaroon. The problem is to solve:
.
16-5