Answer:
x=4
Step-by-step explanation:
For any two points of a line, say [tex](x_1,y_1),(x_2,y_2)[/tex] the slope of the line is [tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]. If the slope is undefined, it is because division by zero, then [tex]x_2-x_1=0[/tex], that is, [tex]x_1=x_2[/tex]. This means that all the points of the line have the same x-coordinate. Because (4,7) is on the line and its x coordinate is 4, the points (x,y) of the line satisfy the equation x=4.
