How to find the value of "k"in completing a table of direct variation if u don't have the first entry for "Y"?

Question

Find "k" and complete the table when y=kx

X...| 2 | 4 | --| 7 |

Y...|-- |28|42|--|

Answer 1

y = kx,  so y/x = k

 

You have two values of y and x from the table, (4,28).  Hence:

 

k = y/x = 28/4 = 7

 

So the equation is y = 7x.

 

Now we can complete the table.  For the entry x=2, we can compute y= 7x = 7*2 = 14, so put a 14 below the 2 in the table.  You should be able to complete the rest of the table on your own now.