Transcript Do Now 10/18/06 - Howell Township Public Schools

Do Now 10/14/09
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Take out HW from last night.
 Textbook
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p.179-181 #4-36 even
Copy HW in your planner.
 Textbook
p. 187 #4-30 even
 “Pop” Quiz sections 3.5-3.8 Friday
Homework
Textbook p.179-181 #4-36 even
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4) 55%
6) 51
8) 21
10) 44%
12) 27
14) 176.3
16) 210
18) 137.5
20) p% should be multiplied
by 95; p% = 20%
22) 85%
24) 33.8
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26) 16%
28) 72%
30) Equation; multiply the
base times the percent to find
the part.
32) 5y
34) 200 laps
36)
Year
Hikers who
Started
Hikers who
Completed
Percent
Completion
2001
2380
395
16.6%
2002
1880
376
20%
2003
1750
352
20%
Objective
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SWBAT rewrite equations and formulas
Section 3.8, “Rewrite Equations
and Formulas”
Literal Equationan equation where the coefficients and
constants are replaced by letters.
The equation 2x + 5 = 11 has the general form
ax + b = c.
Solving a Literal Equation
Solve ax +b = c for x. Then use the solution to solve
2x + 5 = 11.
SOLUTION
STEP 1 Solve ax + b = c for x.
ax + b = c
ax = c – b
c–b
x=
a
Write original equation.
Subtract b from each side.
Assume a = 0. Divide each side by a.
Solving a Literal Equation
STEP 2 Use the solution to solve 2x + 5 = 11.
c–b
x = a
11 – 5
= 2
=3
ANSWER
Solution of literal equation.
Substitute 2 for a, 5 for b, and 11 for c.
Simplify.
The solution of 2x + 5 = 11 is 3.
Try It Out
Solve the literal equation for x . Then use the
solution to solve the specific equation
1. Solve a – bx = c for x.
SOLUTION
STEP 1 Solve a – bx = c for x.
a – bx = c
Write original equation.
– bx = c – a Subtract a from each side.
a–c
x=
b
Assume b = 0. Divide each side by – 1b.
Try It Out
STEP 2 Use the solution to solve 12 – 5x = –3.
a–c
x = b
12 – (–3)
=
5
=3
ANSWER
Solution of literal equation.
Substitute a for 12, –3 for c, and 5 for b.
Simplify.
The solution of 12 – 5x = –3 is 3.
Try It Out
2.
Solve a x = bx + c for x.
SOLUTION
STEP 1 Solve a x = bx + c for x.
a x = bx + c Write original equation.
a x – bx = c
c
x=
a–b
Subtract bx from each side.
Assume a = 0. Divide each
side by a – b.
Try It Out
STEP 2 Use the solution to solve 11x = 6x + 20.
c
x =a–b
20
= 11 – 6
=4
ANSWER
Solution of literal equation.
Substitute a for 11, 20 for c, and
6 for b.
Simplify.
The solution of 11x = 6x + 20. is 4.
Rewriting Equations with
Multiple Variables
An equation or formula with 2 or more
variables, such as 3x + 2y = 8 or A = ½bh,
can be rewritten so that one variable is a
function of the other variable(s).
3x + 2y = 8
This equation can be rewritten
so that y is a function of x.
A = ½bh
This equation can be rewritten
so that you can solve for h.
Try It Out
Write 3x + 2y = 8 so that y is a function of x.
3x + 2y = 8
2y = 8 – 3x
y= 4– 3 x
2
Write original equation.
Subtract 3x from each side.
Divide each side by 2.
Try It Out
1
The area A of a triangle is given by the formula A = bh
2
where b is the base and h is the height.
a.
Solve the formula for the height h.
SOLUTION
a.
1
A = 2 bh
2A = bh
2A
=h
b
Write original formula.
Multiply each side by 2.
Divide each side by b.
Try It Out
b.
Use the rewritten formula to find the
height of the triangle shown, which
has an area of 64.4 square meters.
Substitute 64.4 for A and 14 for b in the rewritten
formula.
2A
h= b
2(64.4)
=
14
= 9.2
ANSWER
Write rewritten formula.
Substitute 64.4 for A and 14 for b.
Simplify.
The height of the triangle is 9.2 meters.
Rewrite the following formulas in
terms for each variable.
Temperature
5
C  ( F  32)
9
Profit
P I E
Distance Traveled
d  rt
Simple Interest
I  Pr t
Temperature
Distance Traveled
d  rt
5
C  ( F  32)
9
9
F  (C  32)
5
Profit
P I E
I  PE
E  I P
d
r
t
d
t
r
Simple Interest
I  Pr t
I
P
rt
I
r
Pt
I
t
Pr
Challenge
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The surface area of a cone is given by the formula
below. Solve for the length.
S  rl  r
S
l
r
r
2
Homework
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Textbook p. 187 #4-32 even