functions problem

Question

For which values of x will the relation not be a function?

R={(x2+7x, 3), (−6, 4)}

Answer 1

Hi Kiranpreet, the relation will not be a function when the value of x² +7x is equal to -6. When this occurs, x will have two y values.

 

x² + 7x = -6

 

x² + 7x + 6 = 0

 

Factoring:

 

x² + 7x + 6 = (x + 6) * (x + 1) = 0

 

Then:

 

x + 6 = 0

 

x = -6

 

And:

 

x + 1 = 0

 

x = -1

 

The values of x when the relaion will not be a function: x = -1 or x = -6.

 

Check:

 

x² + 7x, substitute -6 for x:

 

36 - 42 = -6

 

Substitute -1 for x:

 

1 - 7 = -6

 

Questions?