Transcript Solving Equations

Using symbols instead of numbers
What number can be added to 21 to get
50?
 + 15 = 27
7 x  = 56
Sometimes questions have a missing
number that you need to find.
Using symbols instead of numbers
What number can be added to 21 to get
50? 29
22 + 15 = 27
7 x 8 = 56
Sometimes questions have a missing
number that you need to find.
Using symbols instead of numbers
We often use a symbol to represent that
missing number. Sometimes this is a
letter.
P + 43 = 80
4 x n = 24
Using symbols instead of numbers
We can use a variety of strategies to
solve these:
TRIAL & ERROR
TRIAL & IMPROVEMENT
INVERSES
Using symbols instead of numbers
TRIAL & ERROR – also known as guesswork!
This is the most basic method. Guess
various numbers and see if they work. It is
not very efficient and doesn’t always give
you the answer.
26 + w = 94
Using symbols instead of numbers
TRIAL & ERROR – also known as guesswork!
This is the most basic method. Guess
various numbers and see if they work. It is
not very efficient and doesn’t always give
you the answer.
26 + w = 94
80?
Using symbols instead of numbers
TRIAL & ERROR – also known as guesswork!
This is the most basic method. Guess
various numbers and see if they work. It is
not very efficient and doesn’t always give
you the answer.
26 + w = 94
80? x
Using symbols instead of numbers
TRIAL & ERROR – also known as guesswork!
This is the most basic method. Guess
various numbers and see if they work. It is
not very efficient and doesn’t always give
you the answer.
26 + w = 94
70?
Using symbols instead of numbers
TRIAL & ERROR – also known as guesswork!
This is the most basic method. Guess
various numbers and see if they work. It is
not very efficient and doesn’t always give
you the answer.
26 + w = 94
70? x
Using symbols instead of numbers
TRIAL & IMPROVEMENT – educated
guesswork that gets more accurate!
This method usually gets you to the answer,
but can take a long time. It helps if you say
if the answer is too big, too small, or
correct.
26 + w = 94
80? gives 106 – too big!
So lets look at numbers less than 80.
Using symbols instead of numbers
TRIAL & IMPROVEMENT – educated
guesswork that gets more accurate!
This method usually gets you to the answer,
but can take a long time. It helps if you say
if the answer is too big, too small, or
correct.
26 + w = 94
70? gives 96 – too big!
So lets look at numbers less than 70.
Using symbols instead of numbers
TRIAL & IMPROVEMENT – educated
guesswork that gets more accurate!
This method usually gets you to the answer,
but can take a long time. It helps if you say
if the answer is too big, too small, or
correct.
26 + w = 94
60? gives 86 – too small!
So lets look at numbers between 60 and 70.
Using symbols instead of numbers
TRIAL & IMPROVEMENT – educated
guesswork that gets more accurate!
This method usually gets you to the answer,
but can take a long time. It helps if you say
if the answer is too big, too small, or
correct.
26 + w = 94
65? gives 91 – too small!
So lets look at numbers between 65 and 70.
Using symbols instead of numbers
TRIAL & IMPROVEMENT – educated
guesswork that gets more accurate!
This method usually gets you to the answer,
but can take a long time. It helps if you say
if the answer is too big, too small, or
correct.
26 + w = 94
67? gives 93 – too small!
So lets look at numbers between 67 and 70.
Using symbols instead of numbers
TRIAL & IMPROVEMENT – educated
guesswork that gets more accurate!
This method usually gets you to the answer,
but can take a long time. It helps if you say
if the answer is too big, too small, or
correct.
26 + w = 94
69? gives 95 – too big!
So lets look at numbers between 67 and 69.
Using symbols instead of numbers
TRIAL & IMPROVEMENT – educated
guesswork that gets more accurate!
This method usually gets you to the answer,
but can take a long time. It helps if you say
if the answer is too big, too small, or
correct.
26 + w = 94
68? Gives 94 – correct!
Using symbols instead of numbers
TRIAL & IMPROVEMENT – educated
guesswork that gets more accurate!
This method usually gets you to the answer,
but can take a long time. It helps if you say
if the answer is too big, too small, or
correct.
26 + w = 94
w = 68
Using symbols instead of numbers
INVERSES – using the “undo” method.
This method will always get you the answer,
and will often be the quickest method. It
is, however, slightly trickier.
26 + w = 94
The INVERSE of + is -
Using symbols instead of numbers
INVERSES – using the “undo” method.
This method will always get you the answer,
and will often be the quickest method. It
is, however, slightly trickier.
w = 94 - 26
The INVERSE of + is -
Using symbols instead of numbers
INVERSES – using the “undo” method.
This method will always get you the answer,
and will often be the quickest method. It
is, however, slightly trickier.
w = 68
The INVERSE of + is -
Using symbols instead of numbers
INVERSES – using the “undo” method.
This method will always get you the answer,
and will often be the quickest method. It
is, however, slightly trickier.
d x 9 = 54
The inverse of x is ÷
Using symbols instead of numbers
INVERSES – using the “undo” method.
This method will always get you the answer,
and will often be the quickest method. It
is, however, slightly trickier.
d = 54 ÷ 9
The inverse of x is ÷
Using symbols instead of numbers
INVERSES – using the “undo” method.
This method will always get you the answer,
and will often be the quickest method. It
is, however, slightly trickier.
d=6
The inverse of x is ÷
Using symbols instead of numbers
Try these:
6 + a = 19
b + 43 = 60
15 – c = 2
d – 26 = 90
e x 4 = 32
7 x f = 77
g ÷ 10 = 120
300 ÷ h = 6
Be careful with these ones
Using symbols instead of numbers
Try these:
6 + a = 19
b + 43 = 60
15 – c = 2
d – 26 = 90
e x 4 = 32
7 x f = 77
g ÷ 10 = 120
300 ÷ h = 6
a=
b=
c=
d=
e=
f=
g=
h=
Using symbols instead of numbers
Try these:
6 + a = 19
b + 43 = 60
15 – c = 2
d – 26 = 90
e x 4 = 32
7 x f = 77
g ÷ 10 = 120
300 ÷ h = 6
a = 19 - 6
b = 60 – 43
c = 15 - 2
d = 90 + 26
e = 32 ÷ 4
f = 77 ÷ 7
g = 120 x 10
h = 300 ÷ 6
Using symbols instead of numbers
Try these:
6 + a = 19
b + 43 = 60
15 – c = 2
d – 26 = 90
e x 4 = 32
7 x f = 77
g ÷ 10 = 120
300 ÷ h = 6
a = 13
b = 17
c = 13
d = 116
e=8
f = 11
g = 1200
h = 50