Transcript do the same to each side

Solving Equations using the
Balance method
x x x 4
13
What can
x be?
Remember: to keep the scales
balanced - do the same to
each side
x x x 4
13
take 4 off each side
x x x
9
Now divide 9 equally between the 3 boxes
So x = 3
Now lets see what this looks like using
algebra:
x x x 4
13
This picture can be written as
3x + 4 = 13
Now take 4 off each side
3x + 4 = 13
-4 -4
3x
= 9
the picture would now look like this
x x x
9
Now divide 9 equally between the 3 boxes
x
x
9
3
=
= 3
Example 2
Solve the equation 4x - 3 = 17 using the
balance method
Remember: to keep the scales
balanced - do the same to
each side
This time we need to add 3 to each side
4x - 3
+3
4x
x
x
= 17
+3
= 20
20
= 4
= 5
Example 3
Solve the equation 5x + 7 = 3x + 13 using
the balance method
Remember: to keep the scales
balanced - do the same to
each side
5x + 7
-7
5x
-3x
2x
x
x
= 3x + 13
-7
= 3x + 6
-3x
=
6
6
=
2
= 3