Algebra 1 Common Core Student Edition, Grade 8-9

Choose an appropriate

form ula and solve it fo r

the variable you need to

fin d. S ubstitute w h a t you

know into the rewritten

form ula. Simplify.

Think
How do you know
w h ich fo rm u la to use?
Read th e in fo rm a tio n
given in th e p roblem.
This p ro b le m gives you
a m easure o f tim e a nd a
distance. You need to fin d
the rate, so use d = rt.

SSSB S^ lLesson 2- - 5 Literal Equations and Formulas

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Pr o b l em 3 Rewriting a Geometric Formula

What is the radius of a circle with circumference 64 ft? Round to the nearest tenth.

Use 3.14 for tt.

C 2irr

277 277

277

64

277

10.2

C = 277 r Write the appropriate formula.

D iv id e ea ch sid e b y 277.

Simplify.

Substitute 64 for C.

Simplify. Use 3.14 for tt.

= r

r

r

The radius of th e circle is ab o u t 10.2 ft.

^ G o t It? 3. W hat is th e h eight of a triangle th a t has an area of 24 in.2 an d a base w ith a

length of 8 in.?

G ot It? 4. Pacific gray w hales m igrate annually from

th e w aters n e a r Alaska to th e w aters n e a r Baja

California, Mexico, an d back. The w hales travel a distance of ab o u t 5000 mi

each way at an average rate of 91 m i p e r day. About how m any days does it

take th e w hales to m igrate one way?

Rewriting a Formula

Biology The m onarch butterfly is the only butterfly

that migrates annually north and south. The

distance that a particular group of m onarch

butterflies travels is shown. It takes a typical

butterfly about 120 days to travel one way.

What is the average rate at which a butterfly

travels in miles per day? Round to the

nearest mile per day.

d = rt Write the appropriate formula.

l = r

1700

120

14

Divide each side by t.

Simplify.

Substitute 1700 for d and 120 fo r t.

Simplify.

The butterflies travel at a n average rate of about

14 m i p er day.