Final answer:
The y-coordinate is 12 when the x-coordinate is 4 for the equation y = 3x.
Step-by-step explanation:
To find the y-coordinate when the x-coordinate is 4 in the equation y = 3x, we need to substitute x = 4 into the equation and solve for y.
Substituting x = 4, we get y = 3(4) = 12. Therefore, when the x-coordinate is 4, the y-coordinate is 12.
Graphically, the equation y = 3x represents a straight line with a slope of 3 and a y-intercept of 0. If we trace the graph of this equation on a calculator and input x = 4.
Substituting x = 4 into the equation gives y = 3(4) = 12.
Therefore, when the x-coordinate is 4, the y-coordinate is 12.
In other words, the point with x = 4 on the graph of y = 3x is (4, 12).