Question

*I will give you meddles and become you're fan, just can someone please help me with this question? I've been stuck on this for like a hour now.*

Use the chart below to Find the equation of the line in the graph, and mathematically model the scenario using function notation where cost is a function of number of minutes.

Answer 1

@ganeshie8 @geerky42 @Hero

Answer 2

can you identify two points on that blue line?

Answer 3

(0,20) & (700,50) ?

Answer 4

I agree with (0,20)

but (700,50) is a bit harder to agree with

Answer 5

for me, I would say (0,20) and (400,40)

Answer 6

Okay, now i always get stuck while trying to put it into a equation.

Answer 7

after you get these two points, you find the slope

m = (y2 - y1)/(x2 - x1)

m = (40 - 20)/(400-0)

m = 20/400

m = 1/20


Hopefully you can see how I get the slope of 1/20 ?

Answer 8

when its at 20/40 did you divide by 20?

Answer 9

20/400 reduces to 1/20

you divide both parts by the GCF 20

Answer 10

alright, now that we have 1/20 what do we do?

Answer 11

then we use this slope with either point to get the y-intercept


let's say we use the point (400,40)

y = mx + b

y = (1/20)*x + b

40 = (1/20)*(400) + b

40 = 20 + b

40 - 20 = b

20 = b

b = 20

So the y-intercept is 20

And you can look at the point (0,20) that is on the line as well. This point immediately tells you what the y-intercept is because x = 0 here and it crosses the y axis at this point

Answer 12

So to recap, we got

m = 1/20 (slope)
b = 20 (y-intercept)

So...

\[\Large y = mx + b\]

\[\Large y = \frac{1}{20}x + b\]

\[\Large y = \frac{1}{20}x + 20\]

is your equation

Answer 13

hopefully it all makes sense?

Answer 14

The equation I got; y = 1/20x + 20 where x is minutes and f(x) is the cost in dollars.

Answer 15

that is correct, the answer is

[\Large y = \frac{1}{20}x + 20\]

or

[\Large f(x) = \frac{1}{20}x + 20\]

Answer 16

x is the number of minutes
y or f(x) is the cost in dollars

Answer 17

Thank you so much, you helped me so much!!(:

Answer 18

Can you maybe help me on another one? (:

Answer 19

I'm glad I have and sure, I can do another