Jessica is selling books during the summer to earn money for college. She earns a commission on each sale but has to pay for her own expenses.
After a month of driving from neighborhood to neighborhood and walking
door-to-door, she figures out that her weekly earnings are approximately a
linear function of the number of doors she knocks on.
She writes the equation of the function like this: E(x) = 10x - 30, where x is the
number of doors she knocks on during the week and E(x) is her earnings for
the week in dollars.
Which of the following are reasonable interpretations of the y-intercept of
Jessica's function?
Check all that apply.
A. She can earn $10 per week even if she does not knock on any
doors
B. Her expenses are $30 per week.
c. If she does not knock on any doors at all during the week, she will
lose $30
D. She will lose $10 per week if she does not knock on any doors.

C. if 10x is the door she have to knock so the -30 is how much she will earn during the week and if she doesn't knock any then she will lose the whole $30 dollars . sorry i can't explain myself good but i think it is so

B and C (took the test)

Step-by-step explanation:

B. Her expenses are $30 per week

C. If she does not knock on any doors at all during the week, she will lose $30.

let's add {f(x)=x+1}f(x)=x+1 and {g(x)=2x}g(x)=2x together to make a new function.

f(x)+g(x) =(x+1)+(2x)=x+1+2x=3x+1

let's call this new function hh. so we have:

{h(x)}={f(x)}+{g(x)}{=3x+1}h(x)=f(x)+g(x)=3x+1

we can also evaluate combined functions for particular inputs. let's evaluate function hh above for x=2x=2. below are two ways of doing this.

method 1: substitute x=2x=2 into the combined function hh.

h(x)

h(2)

​    

=3x+1

=3(2)+1

=7

​ since h(x)=f(x)+g(x)h(x)=f(x)+g(x), we can also find h(2)h(2) by finding f(2) +g(2)f(2)+g(2).

first, let's find f(2)f(2):

f(x)

f(2)

​    

=x+1

=2+1

=3

​  

now, let's find g(2)g(2):

g(x)

g(2)

​    

=2x

=2⋅2

=4

​  

so f(2)+g(2)=3+4=\greend7f(2)+g(2)=3+4=7.

notice that substituting x =2x=2 directly into function hh and finding f(2) + g(2)f(2)+g(2) gave us the same answer!