Graph of function

[Videoorchard]

Hi Tommy,

I have a doubt regarding a graph-function oriented problem from algebra practice question. (Easy set)

Problem:
How did author derive the values for F(x) coloum? Also, Could you please elucidate on how the value 4 was put in the coloum even though it is not marked/plotted in the graph?

Source:
Problem 9
Pg 146
Algebra strategy guide

[n00bpron00bpron00b]

Hi Tommy,

Even I have a doubt in this problem. Instead of the tabular form can we just do it the following way ?

1) when x = 1 : f(1) = 1 + 2 = 3
But as per the graph the value of f(1) = 5

2 x = -1 : f(-1) = -1+1 = 0
going by the graph the value of f(-1) = 0
(-1,0) which satisfies

So the answer -1

Thanks

[tommywallach]

Hey Guys,

The thing to remember about a graph-based function question is that f(x) is just a stand in for the y-coordinate. So when you're asked:

When is f(x) = x + 1

All they're really asking is when is y = x + 1, or put in simple, English, at what point is the y value ONE bigger than the x value.

We can see (visually) that this is true when x = -1, because y = 0 at that point. There's no way to "solve" this, because the graph doesn't represent a function with an equation. It's just an arbitrary squiggle.

-t