For this case we have that by definition, the equation of a line of the slope-intersection form is given by:
![y = mx + b](https://img.qammunity.org/2020/formulas/mathematics/high-school/fc4cgm6covys37zv2opmmp9ps4jxyjepvh.png)
Where:
m: It's the slope
b: It is the cut-off point with the y axis
The slope can be found using the formula:
![m = \frac {y_ {2} -y_ {1}} {x_ {2} -x_ {1}}](https://img.qammunity.org/2020/formulas/mathematics/middle-school/cclrk8k9bxv15y05i3ra8kmqckbcx942t8.png)
We have the following points:
![(x_ {1}, y_ {1}): (-2,7)\\(x_ {2}, y_ {2}): (4,1)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/usohy7kc72qsilwvu9ycgc83xyuieee4ug.png)
Thus, the slope is:
![m = \frac {1-7} {4 - (- 2)} = \frac {-6} {4 + 2} = \frac {-6} {6} = - 1](https://img.qammunity.org/2020/formulas/mathematics/middle-school/a3n2kwzhtaeshhz95hrplc30w0noaszjx5.png)
Thus, the equation is of the form:
![y = -x + b](https://img.qammunity.org/2020/formulas/mathematics/middle-school/mc8lib3aoq0y2uu6e9bex0j24e5ns9duig.png)
We substitute a point and find "b":
![1 = -4 + b\\1 + 4 = b\\b = 5](https://img.qammunity.org/2020/formulas/mathematics/middle-school/frl2mgeir945tf8qwt5jlgipkx03jqmphu.png)
Finally, the equation is:
![y = -x + 5](https://img.qammunity.org/2020/formulas/mathematics/middle-school/95vfvlxn55ivbxcj2gsmetaq740uc3t79i.png)
Answer:
![y = -x + 5](https://img.qammunity.org/2020/formulas/mathematics/middle-school/95vfvlxn55ivbxcj2gsmetaq740uc3t79i.png)