Math help! In comments : 3

Question

anonymous · Answer

Okay, the question is: Use function notation to write the equation of the line.

anonymous · Answer

Here is the graph:

anonymous · Answer

attachment

anonymous · Answer

I know the correct answer is f (x) = 4x + 4  I just don't know WHY that's the correct answer.

mathmate · Answer

As a first step, are you able to find the slope and the y-intercept from the graph?

mathmate · Answer

The standard equation is 
y=mx + b
m=slope
b=y-intercept

mathmate · Answer

Can you try to tell me how you'd find each of the two?

anonymous · Answer

I have no idea. : /

mathmate · Answer

To find the y-intercept, you read from the graph where the graph cuts the y-axis.
What would that be?

anonymous · Answer

4.

mathmate · Answer

Excellent, since b=y-intercept, you just found the equation to be
y=mx+4.
Next step is to find the slope.
To find the slope, start from any convenient point, read off y of that point.
Can you do that?

mathmate · Answer

@SmokeyRiver still there?

mathmate · Answer

oh well, I'll be back after supper!

anonymous · Answer

Whoops. Sorry, I'm on Woozworld. xD Anyway, yea. What do you mean by 'read off?'

anonymous · Answer

Sigh. I gotta go. It's allright I have enough questions completed anyway, so I'll pass. Thanks!

mathmate · Answer

As an example of reading from a graph:
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