Algebra 1 Common Core Student Edition, Grade 8-9

(Marvins-Underground-K-12) #1
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.
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