Billy started with 2 poems in his journal. Then he started writing 4 poems each day. Which of the following graph represents Billy's poem writing?

Question

anonymous · Answer

@mathstudent55 @freckles

mathstudent55 · Answer

Before we look at graphs, can you come up with an equation for this function?
Let's say the number of days is x, and the number of poems is y.

mathstudent55 · Answer

the number of poems = a function of the number of days
               y                =              a function of x

anonymous · Answer

so the slope could be 2?

mathstudent55 · Answer

You can use the slope-intercept form:

$y = mx + b$

b is the y-intercept. That is the number you have at zero x-value.
The slope is what accounts for what changes, in this case, daily.

anonymous · Answer

so y=2x+1

mathstudent55 · Answer

the number of poems = a function of the number of days
                 y              =            a function of x
                 y              = fixed beginning amount    +     daily additional amount

mathstudent55 · Answer

No.
Look at my last line above.
y, the number of poems, is the sum of the beginning amount and the daily additional amount.
What is the beginning amount?
Hint: "Billy started with 2 poems in his journal."

anonymous · Answer

2x

anonymous · Answer

would the points be (4,2) and (0,2)

mathstudent55 · Answer

No. No x.
The fixed amount never changes. It is not dependent on x.
The fixed amount is simply 2 since Billy started with 2 poems in his journal.

anonymous · Answer

Ok, so the points would be (0,2) (1,6) and (2,10)

anonymous · Answer

am i right?

mathstudent55 · Answer

The daily additional amount depends on the day.
He adds 4 poems per day. Day is x, so
after day 1 he has 4 * 1 extra poems.
after day 2 he has 4 * 2 extra poems
after day 3 he has 4 * 3 extra poems
after day 4 he has 4 * 4 extra poems
this pattern goes on and on...
after day x he has 4 * x extra poems

mathstudent55 · Answer

Since y, the number of poems in his journal is given by the fixed number of poems he started with plus the daily additional poems, we can write:

y = 2 + 4x

which can be rewritten as 

y = 4x + 2

anonymous · Answer

Ok! Thanks :)

anonymous · Answer

what would be some points if I graphed that?

mathstudent55 · Answer

Yes, your points are correct because they are all points in the equation
y = 4x + 2

anonymous · Answer

(0,2) (1,6) ??

anonymous · Answer

If I open another can u help again?

mathstudent55 · Answer

sure