## selenamalter 2 years ago which product is undefined?

1. selenamalter

2. uri

matrics?

3. selenamalter

yeah

4. uri

5. selenamalter

A. AB B. BA C. DB D. CD would these help

6. uri

wait so like you're asking me to slove all this and tell you from this which one's are impossibe?

7. uri

solve*

8. selenamalter

I think so :/ you see, the problem is, i dont know how to do it

9. amistre64

matrix multiplication requires that the number of columns in the first one, matches the number of rows in the second one

10. uri

Okay wait :3

11. amistre64

|dw:1371047591398:dw|

12. selenamalter

so? BD ???

13. amistre64

does B have a different number of columns then D has rows?

14. amistre64

essentially, we need to be able to pair up vectors|dw:1371047676408:dw| if we cant pair up the vectors, we can perform the operations

15. giolefpatceid

For each multiplication, count the number of columns for the first table and the number of rows for the second table. If they are equal, the multiplication is valid. Otherwise the product it is undefined.

16. uri

It's BA.

17. uri

Option no.B

18. amistre64

if we notate this in row,column format A=3,2 B=2,2 C=3,1 D=1,2 (r,c)(r,c) | | these numbers have to equal

19. amistre64

CD = 3,1 1,2 is valid DB = 1,2 2,2 is valid AB = 3,2 2,2 is valid BB = 2,2 2,2 is valid i think thats all the valid ones

20. giolefpatceid

For the AB multiplication. A has 2 columns, B has 2 rows, so the multiplication is valid. You do the same thing for the rest.