Answer:
y = 6
Explanation:
You want the equation of the line with slope 0 through point (4, 6).
Point-slope equation
The point-slope equation of a line is ...
y -k = m(x -h) . . . . . . . line with slope m through point (h, k)
Simplified
Using the given values, m=0 and (h, k) = (4, 6), we have ...
y -6 = 0(x -4)
y -6 = 0 . . . . . . . . equation of the line in general form
y = 6 . . . . . . . . . . equation of the line in slope-intercept form
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Additional comment
It should be obvious that a line with slope 0 has the equation ...
y = constant
To make the line go through a point with a particular y-value, the constant must be that y-value.