Question

how do you find the y intercept in two ordered pairs. Ex. (2,40 and (4, 9)
Not a real problem, but i need to know how to do it.

Answer 1

Start by finding the slope. Do you know the slope formula?

Answer 2

yeah, i found the slope, in my problem its 1/2

Answer 3

The slope between (2,40) and (4,9) isn't 1/2. I assume you're working with two different points?

Answer 4

no.. haha i was just wondering how to do this. My two ordered pairs in my problem are (2,120) and 4, 240)

Answer 5

Ah, ok. So the next step is to take the slope you found, and one point and plug them both into the point slope form of a line.

Answer 6

\[y-k = m(x-h)\]

Where m is the slope, and (h,k) is one of the points.

Answer 7

to find the y-intercept?

Answer 8

yes.

Answer 9

oh, thanks

Answer 10

so what would the y intercept be? 6?

Answer 11

Once you have the equation for the line you can find the y intercept by plugging in a 0 for x and solve for y.

Or you can find the x intercept by plugging in a 0 for y and solving for x.

Answer 12

\(y-120 = \frac{1}{2}(x - 2)\)\[\implies y = \frac{1}{2}x - 1 + 120\]
Plugging in 0 for x..
\[\implies y = 0 -1 + 120 = 119\]

Answer 13

Does that make sense?

Answer 14

yes. alot actually. Thank you. :)