Continuous across a domain problem: cx + 1 for x >= 7, an

[PaintballEngineer]

F(x)=cx+1 if x greater than or equal to 7
F(x)=cx^2-1 if x less than 7

What constant value of C makes f(x) continuous across (-infinity, +infinity)?

I'm not real sure how to do this.

 

[stapel]

Hint: When x = 7, what is cx + 1? When x = 7 (pretending for the moment you were allowed to plug this in), what is cx² - 1? For the function to be continuous (connected), what must be true about the values of cx + 1 and cx² - 1 at x = 7?

Eliz.

 

[PaintballEngineer]

They must be the same?

 

[stapel]

They must be the same?

The two ends must meet at the "middle" (at x = 7). Use this fact to create an equation, and then solve for the value of c.

Eliz.

 

[PaintballEngineer]

so...

cx+1=cx^2-1

I'm really not sure here. I've tried several things and I'm still not getting it.

 

[PaintballEngineer]

snap, just figured it out. Thanks for the help.