Today:

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• Today
• Lecture on Section 2.6 More word problems!
• REMINDER
• Gateway 3 needs to be completed by 5 PM Thursday,
  11/5 (see handout for more details).

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CLOSE YOUR LAPTOPS
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Section 2.6

• A formula is an equation that states a
  relationship among two or more variables.

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A lw (Area of a rectangle length
width) I PRT (Simple Interest
Principal Rate Time) P a b c
(Perimeter of a triangle side a side b side
c) d rt (distance rate time) V lwh
(Volume of a rectangular solid length
width height)
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Problem Find the area of a rectangle with a
length of 5 inches and a width of 10 inches using
the formula A lw Solution l 5 and w
10, so A 510 50 square inches Problem
Find the distance traveled in 4 hours by an
airplane flying at a speed of 720 mph using the
formula d rt Solution r 720 and t 4,
so d 7204 2880 miles (distance rate
time)
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Problem from todays homework
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A flower bed is in the shape of a triangle with
one side twice the length of the shortest side,
and the third side is 30 feet more than the
length of the shortest side. Find the dimensions
if the perimeter is 102 feet.
DRAW A PICTURE!!!
Read and reread the problem. Recall that the
formula for the perimeter of a triangle is P a
b c .where a, b and c represent the lengths
of the three sides of the triangle. If we
let x the length of the shortest side, then
2x the length of the second side, and x
30 the length of the third side.
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Formula P a b c
x the length of the shortest side (a) 2x the
length of the second side (b) x 30 the
length of the third side (c) P perimeter 120
feet (given in the problem statement.) Substitute
these items into the formula to get
102 x 2x x 30
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102 x 2x x 30
102 4x 30 (simplify right side)
72 4x (simplify both sides)
18 x (simplify both sides)
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Check If the shortest side of the triangle is
18 feet, then the second side is 2(18) 36 feet,
and the third side is 18 30 48 feet. This
gives a perimeter of P 18 36 48 102 feet,
the correct perimeter. Always check your
answer! State The three sides of the triangle
have lengths of 18 feet, 36 feet, and 48 feet.
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Problem from todays homework(As we do this
problem, we will review adding and multiplying
decimal numbers without using a calculator.)
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Problem from todays homework(To do this
problem without using a calculator, convert the
decimal number 1.5 into the mixed fraction
.)
Note The formula for the volume of a tank like
this is V lwh where V volume, l
length, w width and h height. (You will not
have to memorize formulas for tests or quizzes
we will give them to you. If you need a formula
for a homework problem, click help me solve
this.)
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• Steps for solving formulas
• Multiply to clear fractions.
• Use distributive property to remove grouping
  symbols like parentheses.
• Combine like terms to simply each side.
• Get all terms containing specified variable on
  the same time, other terms on opposite side.
• Isolate the specified variable by dividing by its
  number coefficient on both sides of the equation.

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Problem from todays homework
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Problem from todays homework
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Problem from todays homework
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Reminder

• This homework on Section 2.6 is due at start of
  next class session.

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Note to instructors The remaining slides
contain additional problems from todays homework
that you may want to cover if time allows.
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Problem from todays homework
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Problem from todays homework
155/2 miles (or 127.5)
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Problem from todays homework
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Problem from todays homework