Add o r su b trac t.,,-7 ,2 ,c 4 _ 2 57 27 __9_ 2 8 — + —
25' 3^+ 5 26‘ x 3 27' „3 ?„2 5 x8 3x6- ^ I O^70 a J „ L C ™ -I- 9 +^9 I 8 - — 7 31 « _ + « +! 31 /7 + 3 4 32 5' • - 4
a + 3 a + 5 3U’ w + 2"r m - 7 J I - a + 3 T 4 - f 2 t + l - Exercise Jane walks one m ile from h er house to h er g ra n d p are n ts’ house. ^ S e e P ro b lem 5.
Then she returns hom e, w alking w ith h er grandfather. H er re tu rn rate is
70% of h er rate walking alone. Let r rep resen t h e r rate walking alone.
a. Write an expression for th e a m o u n t of tim e Jane sp en d s walking.
b. Simplify your expression.
c. Suppose Jane’s rate walking alone is 3 m i/h. About how m u ch tim e does she
spend walking?
Apply @ 34. Error Analysis A stu d en t a d d e d two rational expressions as shown.
W hat error did th e stu d en t make? - W riting W hen you use the LCD to a d d or su b tract rational expressions,
will th e answ er always be in sim plest form if you use th e LCD? Explain. - O pen-Ended W rite two rational expressions w ith different denom inators. Find
the LCD an d ad d the two expressions.
Add or subtract.
y2 + 2y - 1 2y2 - 3 h2 + 1 , h
*'■ 3y + 1 3y + 1 ‘ 2t2 - 7 2t2 - 7- 9 + pJ 9 + p3 40.xy z xy z
4.1 q + x ~ 9 42 — ------ 11
4I,S x + 2 2 t — 3 11- Think A b o u ta Plan The g ro u n d sp eed for jet traffic from Los Angeles to New York
City can be ab o u t 100 m i/h faster th a n th e g roundspeed from New York City to
Los Angeles. This difference is d u e to a strong w esterly w ind at high altitudes. If
r is a je t’s groundspeed from New York City to Los Angeles, write an d simplify an
expression for th e roun d -trip air time. The two cities are ab o u t 2500 m i apart.- Can you write an expression for th e air tim e from New York City to Los Angeles?
- In term s of r, w hat is the je t’s g ro undspeed from Los Angeles to New York City?
Can you use this speed to w rite an expression for th e air tim e from Los Angeles
to New York City?
- Rowing A rowing team practices rowing 2 m i u p stream an d 2 m i dow nstream.
The team can row dow nstream 25% faster th a n they can row upstream.
a. Let u represent the team ’s rate rowing upstream. W rite an d simplify an
expression involving u for th e total am o u n t of tim e they sp en d rowing.
b. Let d re p resen t th e team ’s rate rowing dow nstream. W rite an d simplify an
expression involving d for th e total a m o u n t of tim e they sp en d rowing.
c. R easoning Do the expressions you w rote in p arts (a) an d (b) re p resen t th e sam e
time? Explain.
6 8 8 C h a p t e r 11 Rat io nal Expressions and Funct ions