Warm Up

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Warm Up
Problem of the Day
Lesson Presentation
Lesson Quizzes
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Warm Up Solve. 1. x 14 27 2. 50 2x
16 3. 12 4. 6x 72
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33
48
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Problem of the Day Sandra has some pencils.
Kylie has twice as many pencils as Sandra.
Together they have 42 pencils. Write and solve an
equation to find how many pencils each girl has.
x 2x 42 Sandra 14, Kylie 28
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Sunshine State Standards
MA.8.A.4.1 Solve literal equations for a
specified variable.
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Vocabulary
literal equation
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A literal equation is an equation with two or
more variables.
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Additional Example 1A Solving for Variables in
Formulas
Solve each equation for the given variable. A
lw for l
A lw
Divide both sides by w to isolate l.
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Additional Example 1B Solving for Variables in
Formulas
Solve each equation for the given variable. I
prt for t
I prt
Divide both sides by pr to isolate t.
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Check It Out Example 1A
Solve each equation for the given variable.
A lw for w.
lwl
Al

Al

w
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Check It Out Example 1B
Solve each equation for the given variable.
I Prt for P.
Prtrt
Irt

Irt

P
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Additional Example 2 Application
The area of a rectangular table is 30 ft2. What
is the width of the table if the length is 7.5
feet?
First solve the area formula for w because you
want to find the width. Then use the given values
to find w.
A lw
Divide both sides by l to isolate 1.
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Additional Example 2 Continued
The area of a rectangular table is 30 ft2. What
is the width of the table if the length is 7.5
feet?
w 4
The width of the table is 4 feet.
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Check It Out Example 2
The formula V Bh gives the volume V of a
rectangular prism with base area B and height h.
The volume of a rectangular prism is 96 cm3. What
is the height of the prism if base area is 12 cm?
VB
V Bh
h
VB
BhB
9612


VB
h
h 8
The height of the prism is 8 cm.
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Additional Example 3A Solving Literal Equations
with Addition or Subtraction
Solve each equation for the given variable.
c d e for d
Locate d in the equation.
c d e
Add e to both sides of the equation.
c e d
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Additional Example 3B Solving Literal Equations
with Addition or Subtraction
Solve each equation for the given variable.
4x y 1 3x for y
Locate y in the equation.
4x y 1 3x
Subtract 1 from both sides of the equation.
4x 1 y 3x
Add 3x to both sides of the equation.
7x 1 y
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Check It Out Example 3A
Solve each equation for the given variable.
3x 2y y z for z
3x 2y y z
3x 3y z
z 3x 3y
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Check It Out Example 3B
Solve each equation for the given variable.
4t 2s 2t r s for r
4t 2s 2t r s
4t 3s 2t r
2t 2t
2t 3s r
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Additional Example 4 Solving Literal Equations
for a Variable
The equation t m 10e gives the test score t
for a student who answers m multiple-choice
questions and e essay questions correctly. Solve
this equation for e.
t m 10e
Locate e in the equation.
t m 10e
Since m is added to 10e, subtract m from both
sides.
t m 10e
Since e is multiplied 10, divide both sides by 10.
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Check It Out! Example 4
Solve 2k - 4d r for k
2k 4d r
r 4d2
4d 4d
k
r 4d2
2k2

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Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems
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Lesson Quiz
1. Solve 3Y F for Y. 2. Solve g hk for h.
3. Solve 2b 3c d for b. 4. Solve 6 2m n
3n 9 for m. 5. What would be the length of a
rectangle if its perimeter was 72 meters and its
width was 16 meters?
20 m
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Lesson Quiz for Student Response Systems
1. Solve for D. A. B. D V C. D mV D.
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Lesson Quiz for Student Response Systems
2. Solve for m. A. B. D Vm C. DV m D.