# algebra_Balance_scale

Document Sample

```					        Algebra-Balance Scale
Solve simple linear equations using a balance beam
representation.

R.Gallinagh September 2005
Algebra-Balance Scale
.

3x + 3 = x + 7

What does x=?

R.Gallinagh September 2005
Algebra-Balance Scale
.

3x + 3 = x + 7

What do we need to do to make it balance?

R.Gallinagh September 2005
Algebra-Balance Scale
.

3x + 3 = x + 7

We need to put x +7 on other side. Now it is balance

R.Gallinagh September 2005
Algebra-Balance Scale
.

3x + 3 = x + 7
What happens if we move a number 1 from left hand side

No longer balanced……… 3x + 2 does NOT equal x + 7

What do we need to do to make it balance?

R.Gallinagh September 2005
Algebra-Balance Scale
.

3x + 2 = x + 6

We need to move 1 from the other side

We have balance again since 3x + 2 does EQUAL x + 6

R.Gallinagh September 2005
Algebra-Balance Scale
.

3x + 2 = x + 6

Who took 1 away from the right hand side?
3x + 2 obviously does NOT equal x + 5
What must we do to get BALANCE?

R.Gallinagh September 2005
Algebra-Balance Scale
.

3x + 1 = x + 5

YES You are right; we must take away one from the right
hand side
Does 3 x + 1 = x + 5 ……………..Yes it does

R.Gallinagh September 2005
Algebra-Balance Scale
.

3x + 1 = x + 5
Some one has taken 1 away from the right hand side

Does 3x = x + 5 ….The beam tells us it does not.
What do we do for balance?

R.Gallinagh September 2005
Algebra-Balance Scale
.

3x = x + 4
Take 1 away from the right hand side.

It means   3x = x + 4
We don’t have numbers on both sides; but we do have x’s

R.Gallinagh September 2005
Algebra-Balance Scale
.

3x = x + 4

Taking x just from one side caused imbalance
We must take x from other side

R.Gallinagh September 2005
Algebra-Balance Scale
.
Now we have balance with 2x on one side and 4 on the other side

2x = 4

That means x = 2 ………….wow easy

R.Gallinagh September 2005
Algebra-Balance Scale

3x + 3 = x + 7

R.Gallinagh September 2005
Algebra-Balance Scale

3x + 3 = x + 7
3x + 3 - 3 = x + 7 - 3

R.Gallinagh September 2005
Algebra-Balance Scale

3x + 3 = x + 7
3x + 3 - 3 = x + 7 - 3
3x = x + 4

R.Gallinagh September 2005
Algebra-Balance Scale

3x + 3 = x + 7
3x + 3 - 3 = x + 7 - 3
3x = x + 4
3x -x = x - x + 4

R.Gallinagh September 2005
Algebra-Balance Scale

3x + 3 = x + 7
3x + 3 - 3 = x + 7 - 3
3x = x + 4
3x -x = x - x + 4
2x = 4

R.Gallinagh September 2005
Algebra-Balance Scale

3x + 3 = x + 7
3x + 3 - 3 = x + 7 - 3
3x = x + 4
3x -x = x - x + 4
2x = 4
X=2
R.Gallinagh September 2005

```
DOCUMENT INFO
Shared By:
Categories:
Stats:
 views: 130 posted: 6/14/2011 language: English pages: 18