Respuesta :
Solution:
The slope-intercept form of a line with slope m and y-intercept b is given by the following formula:
[tex]y\text{ = mx+b}[/tex]On the other hand, the slope m is given by the following equation:
[tex]m\text{ = }\frac{Y2-Y1}{X2-X1}[/tex]where (X1,Y1) and (X2,Y2) are points on the line. In this case, we can take the points:
(X1,Y1) = (1,2)
(X2,Y2) = (-1,-1)
replacing this data into the slope equation, we get:
[tex]m\text{ = }\frac{-1-2}{-1-1}\text{ = }\frac{-3}{-2}\text{ = }\frac{3}{2}[/tex]thus, the slope of the line would be:
[tex]m\text{ = }\frac{3}{2}[/tex]now, replacing this into the slope-intercept form of the line we get:
EQUATION 1
[tex]y\text{ = }\frac{3}{2}x\text{ + b}[/tex]We only need to find the y-intercept b. For that, take any point on the line, for example (x,y) = (1,2), and replace it into the previous equation:
[tex]2\text{ = }\frac{3}{2}(1)\text{ + b}[/tex]this is equivalent to:
[tex]2\text{ = }\frac{3}{2}+\text{ b}[/tex]solving for b, we get:
[tex]b\text{ = 2- }\frac{3}{2}\text{ = }\frac{1}{2}[/tex]that is:
[tex]b\text{ = }\frac{1}{2}[/tex]finally, replacing this into the EQUATION 1, we get:
[tex]y\text{ = }\frac{3}{2}x\text{ + }\frac{1}{2}[/tex]then, the slope-intercept form of a line with the points (1,2) and (-1,-1) would be:
[tex]y\text{ = }\frac{3}{2}x\text{ + }\frac{1}{2}[/tex]
