The y-intercept is at the point where the line cut the y-axis.
Hence, the y-intercept is 1
[tex]\begin{gathered} \text{Slope}=\frac{y_2-y_1}{x_2-x_1} \\ m=\frac{3-0}{-1-0} \\ m=\frac{3}{-1}=-3 \end{gathered}[/tex]
Hence, the slope is -3
Comparing the values to the equation y = =-3x +1, the equation is valid for the line.
