Question 135655: y = 2x + 4 is the equation and they want to know what the orderd pair of the point that crosses the y axis is. We don't know what the orderd pair means.
Found 2 solutions by stanbon, solver91311:
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! y = 2x + 4 is the equation and they want to know what the orderd pair of the point that crosses the y axis is. We don't know what the orderd pair means.
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The y-axis contains all the points where x=0.
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If y = 2x+4, let x=0 so you can solve for "y":
y = 2*0+4
y = 4
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The line crosses the y-axis at the point (0,4); this is called the y-intercept.
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Cheers,
Stan H.
Answer by solver91311(24713)  (Show Source):
You can put this solution on YOUR website! An ordered pair is two numbers the first of which is the x-coordinate (how far and which direction, i.e. left or right, you go to find the point on the graph horizontally) and the second is the y-coordinate (how far and in which direction, i.e. up or down, you go to find the point on the graph vertically) It is called an ordered pair because the two numbers are always in the same order, x first, then y. The notation is: (x, y). (x is traditionally the horizontal axis, and y the vertical. You could have p and q axes, or any other set of designators, as long as you are careful to define which is which. Sticking with x and y in their traditional order keeps everyone from becoming horribly confused.)
A linear equation in two variables is a rule that describes a set of ordered pairs, and the set of ordered pairs defined by a given equation gives you a line on the graph. Conversely, every point on the line described by the equation has an ordered pair associated with it, and the x- and y-coordinates given by the ordered pair will, when substituted for x and y in the equation, make the equation a true statement. The x- and y-coordinates of any point NOT on the line will make the equation a false statement.
Your job is to find that one point that the given equation and the y-axis have in common -- their point of intersection. The y-axis has the property that every point on the axis has an x-coordinate of 0. That means that any point that is on the y-axis has an ordered pair of the form (0,y).
So, for your equation, substitute 0 for x and see what y has to be in order to make the equation a true statement.
So the ordered pair where the line represented by and the y-axis intersect is (0,4). This is also the only ordered pair that makes both and the equation that represents the y-axis, namely  , true simultaneously.
Here's a picture:
Hope that helps.
John
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