Question

Darren is finding the equation in the form y=mx+b for a trend line that passes through the points (2, 18) and (–3, 8). Which value should he use as b in his equation?

Answer 1

gradient = (8-18)/(-3-2)
= -10/-5
= 2

y = mx + b , at point ( -3,8 )
8 = 2(-3) + b
8 = - 6 + b
b = 14

we cannot simply take one of the y coordinate as value of b because b is the interception of straight line,not a point

Answer 2

Hello!

B - Y-intercept

First, let's write out the equation by finding the slope


`y = mx + b`


`(8-18)/(-3-2) = (-10)/(-5) = 2`

Our slope is 2. Let's plug this in


`y = 2x + b`

Now let's find the y-intercept. Plug one of the x and y values into the equation. I'll use the ones for (2, 18) since they're positive.


`18 = 2(2) + b 18 = 4 + b 18 - 4 = 4 - 4 + b 14 = b`

He should use the number 14 as the y-intercept. Here's what his equation will look like.


`y = 2x + 14`

Hope I helped! :3