I've tried learning distributive property on khan academy I understand this much
3(9x2) 3x9=27 3x2=6 27+6= 33
but then they added in this Diagram or block chart and it threw me completely off and i can't seem to fathom how to use it could you guys please help me on this one?
http://img96.imageshack.us/img96/5633/cantsolveit.png
3(9x2) 3x9=27 3x2=6 27+6= 33
but then they added in this Diagram or block chart and it threw me completely off and i can't seem to fathom how to use it could you guys please help me on this one?
http://img96.imageshack.us/img96/5633/cantsolveit.png
-
The diagram is there to help you understand how the distributive property makes sense visually. Consider two equivalent ways of finding the number of rectangles in the entire grid.
One way is to find the total number of columns and multiply this by the number of rows.
There are 9 light-colored columns (on the left) and 8 dark-colored columns (on the right), so the total number of columns is 9+8.
There are 5 rows.
So the number of rectangles in the entire grid is 5 x (9 + 8).
The other way is to find the number of light-colored rectangles (on the left), find the number of dark-colored rectangles (on the right), and add these two results.
There are 5 rows.
Since there are 9 light-colored columns, there are 5 x 9 light-colored rectangles.
Since there are 8 dark-colored columns, there are 5 x 8 dark-colored rectangles.
So the number of rectangles in the entire grid is (5 x 9) + (5 x 8).
Thus 5 x (9 + 8) and (5 x 9) + (5 x 8) are two expressions for the number of rectangles in the entire grid. Therefore, 5 x (9 + 8) = (5 x 9) + (5 x 8). So the missing number is 5.
Lord bless you today!
One way is to find the total number of columns and multiply this by the number of rows.
There are 9 light-colored columns (on the left) and 8 dark-colored columns (on the right), so the total number of columns is 9+8.
There are 5 rows.
So the number of rectangles in the entire grid is 5 x (9 + 8).
The other way is to find the number of light-colored rectangles (on the left), find the number of dark-colored rectangles (on the right), and add these two results.
There are 5 rows.
Since there are 9 light-colored columns, there are 5 x 9 light-colored rectangles.
Since there are 8 dark-colored columns, there are 5 x 8 dark-colored rectangles.
So the number of rectangles in the entire grid is (5 x 9) + (5 x 8).
Thus 5 x (9 + 8) and (5 x 9) + (5 x 8) are two expressions for the number of rectangles in the entire grid. Therefore, 5 x (9 + 8) = (5 x 9) + (5 x 8). So the missing number is 5.
Lord bless you today!
-
GettIng 85 twice will not help you to solve. It is only used to verify that the distributive property works.
Report Abuse
-
On your example : 3(9+ 2)= 3*9 + 3*2= 27+6= 33
On the chart, they are showing how distributive property looks in a physical example: it's not something you would want to do to solve the problem.
But lets say you want to give five coats of paint to the school. There are 9 yellow walls and 8 blue walls. And you want to find how many total coats of paint will be given:
So 5(9yellow +8blue ) = 5*9 + 5*8= 45+40= 85
This just demonstrates that you can do the work either way: 5* (9+8) = 5* 17= 85
Here is one way that distributive comes in handy for mental math:
if you want to multiply 5* 23
Then you can think of it as 5(20+3)= 5*20+5*3= 100+15= 115
I hope this helps!
On the chart, they are showing how distributive property looks in a physical example: it's not something you would want to do to solve the problem.
But lets say you want to give five coats of paint to the school. There are 9 yellow walls and 8 blue walls. And you want to find how many total coats of paint will be given:
So 5(9yellow +8blue ) = 5*9 + 5*8= 45+40= 85
This just demonstrates that you can do the work either way: 5* (9+8) = 5* 17= 85
Here is one way that distributive comes in handy for mental math:
if you want to multiply 5* 23
Then you can think of it as 5(20+3)= 5*20+5*3= 100+15= 115
I hope this helps!