Question

What is the equation of the line that passes through the points (-2, 1) and (1, 10)?

3x - y = -7

3x - y = -5

3x - y = 5

x + 3y = -5

Answer 1

Using y = mx + b only:

10 = m + b
1 = -2m + b

b = b

10 - m = 2m + 1
10 - 1 = 2m + 1
9 = 3m
9/3 =m
3 = m

10 - 3 = b
7 = b

Therefore:

y = 3x + 7

Answer 2

thats not one of the choices

Answer 3

First you need to find the slope of the line, or m. The slope is the rise over run. For two points this is equivalent to. \[\frac{ y _{1} - y _{2} }{ x _{1} - _{2} }\] In this case, the slope, or m, is.\[m = \frac{ 1 - 10 }{ -2 - 1} = \frac{ -9 }{ -3 } = 3\] Now we need to find what the y intercept, or b, is. The y intercept is what point on the y-axis the line intersects at. We can calculate this via the following equation.\[y = mx + b\] What we must do is to substitute the slope, m, and one of the points, y and x, with their respective values.\[10 = 3(1) + b\]\[7 = b\] Now that we know the slope and the y intercept we can substitute that into the formula to get our answer of...\[y = 3x + 7\]