Download 2.7 Multiplication Equations

Multiplication
Equations
Unit 2.7
Pages 77-80
Warm Up Problems
Solve the following problems.
1. 72 / 6
12
2. 65 / 5
13
3. 60 / 6
10
4. 91 / 7
13
5. 130 / 5
26
Using the inverse of
multiplication for equations.
3x2 = 6
Objective:
6 3=2
Students will be able to solve
whole number multiplication problems using
the inverse of multiplication which is division,
then check their answers.
The symbol x for
multiplication
was developed
around the
1600’s. The x
symbol is not
used in algebra
because it
resembles the
letter X .
X for
Math?
We know that Division is the inverse (or opposite)
of multiplication because when we write the fact
families for numbers, they appear that way.
3x2=6
6/3=2
6/2=3
2x3=6
Inverse!
The inverse of Multiplication is
Division. Just remember to
“undo” what you just did by…
WHAT YOU DO TO
ONE SIDE, YOU HAVE
TO DO IT TO THE
OTHER SIDE!
We use a fraction bar to show how we
will perform division on each side of
the equation. When we do it to one
side…we do the same to the other.
Isolate the variable
The
Coefficient
is the
number
we use to
divide
both sides
of the
equation
with
4
4m = 32
4 = 4
m= 8
Now we have to Check it.
4m
(8) = 32
32 = 32
YES!
Remember to
keep everything
balanced.
Preform the
INVERSE
(opposite) to
get a solution
3x
Now check it by putting the solution
back into the equation
x= 4
12
Remember to
keep everything
balanced.
Preform the
INVERSE
(opposite) to
get a solution
Now check it by putting the solution
back into the equation
8
w=2
4w
Solve each
equation and
check your
answers.
p = 15
Now you try it!
Share the answer with a partner.
5p = 75
Solve each
equation and
check your
answers.
r=2
Now you try it!
Share the answer with a partner.
16 = 8r
We use variables to find the area of shapes.
The area of a rectangle is 36 square inches.
If the Length is 9 inches, what is the width?
 Underline Important
information.
 Draw a picture
 Label the drawing
 Write and equation
 Solve the problem.
W=4
w
36 sq. in.
9
Length x width = area
9w = 36
We use variables to find the area of shapes.
The area of a rectangle is 45 square inches.
If the width is 5 inches, what is the length?
 Underline Important
information.
 Draw a picture
 Label the drawing
 Write and equation
 Solve the problem.
L = __ sq. in.
5
45 sq. in.
L
Jupiter has 2 times more moons
than Neptune does.
If Jupiter has 16 moons
how many moons does
Neptune have?
Because we are comparing things, we know that we
will have an equation with an equal sign in it.
Jupiter
16 moons
Neptune
2n
Division is the Inverse of Multiplication. When we
add 27 to both sides of the equation we “undo”
the subtraction. This helps us find our solution.
16 = 2n
2 = 2
8 =n
Neptune has 8 moons
Recycling 1 ton of paper saves 17 trees!
How many tons of paper
would be needed to
save 136 trees?
Because we are comparing things, we know that we
will have an equation with an equal sign in it.
Trees
17 t
Total Trees
136
Division is the Inverse of Multiplication. When we
add 27 to both sides of the equation we “undo”
the subtraction. This helps us find our solution.
17t = 136
17 = 17
t=8
tons
We would need 8 tons of paper.
Solve each
equation and
check your
answers.
X=3
Now you try it!
Share the answer with a partner.
7x = 21
Solve each
equation and
check your
answers.
W=9
Now you try it!
Share the answer with a partner.
27 = 3w
Solve each
equation and
check your
answers.
a= 9
Now you try it!
Share the answer with a partner.
90 = 10a
Solve each
equation and
check your
answers.
b= 8
Now you try it!
Share the answer with a partner.
56 = 7b
Solve each
equation and
check your
answers.
C = 11
Now you try it!
Share the answer with a partner.
3c = 33
Solve each
equation and
check your
answers.
n= 6
Now you try it!
Share the answer with a partner.
12 =2n
2.7 Homework
Page 79, due: Tuesday

8-22

8-17