Question

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

Answer 1

Answer:

y = -3x + 4

Step-by-step explanation:

First, we find the slope, and to find the slope;$\frac{y_{2} - y_{1}}{x_{2} - x_{1} }$

Slope : -3

Now we fill in the equation with a point and find the y- intercept:

2 = -3(1) + b

2 = -2 + b

4 = b

y = -3x + 4

Answer 2

Answer:

$y = - 3x + 5$

Step-by-step explanation:

to find the gradient/slope between these points:

$\frac{y_{2} - y_{1}}{x_{2} - x_{1} }$

$\frac{ - 1 -2}{2 - 1} = - 3$

the gradient is -3

we need to write the equation in the form y=mx+c. Choose any of the two coordinates in the question. I'll choose (1,2).

y is 2, x is 1 and m is the gradient which is -3

working out c:

$y = mx + c$

$2 = - 3(1) + c$

$2 = - 3 + c$

add 3 on both sides

$2 + 3 = c$

$c = 5$

final equation:

$y - = - 3x + 5$