document.write( "Question 89147: This is from a worksheet.
\n" ); document.write( "Find the y-intercept of the graph of the equation 5x + 3y -15 = 0. State your answer as an ordered pair.
\n" ); document.write( "I do not understand how to do this. \n" ); document.write( "
Algebra.Com's Answer #64791 by bucky(2189)\"\" \"About 
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Given:
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\n" ); document.write( "5x + 3y -15 = 0
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\n" ); document.write( "You are asked to find the y-intercept and to put the answer in the form of an ordered pair.
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\n" ); document.write( "Let's begin by defining a couple of the terms just to make sure that we know what we are
\n" ); document.write( "trying to do.
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\n" ); document.write( "The y-intercept is the point on the y-axis where the graph crosses.
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\n" ); document.write( "An ordered pair is the way you identify a point on the coordinate system. Each point on
\n" ); document.write( "the coordinate system is identified by an x value and a y value. The convention is to write
\n" ); document.write( "ordered pairs in the form (x, y) where x is the position of the point in the x direction
\n" ); document.write( "and the corresponding y is the position of the point in the y direction. As an example,
\n" ); document.write( "the point (2, -3) is located by going to +2 on the x-axis and drawing a vertical line through
\n" ); document.write( "the +2. Then going to -3 on the y-axis and drawing a horizontal line through that point.
\n" ); document.write( "The point specified by the ordered pair (2, -3) is located where the vertical and horizontal
\n" ); document.write( "lines cross.
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\n" ); document.write( "Perhaps you knew these two definitions already.
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\n" ); document.write( "We can now extend on these definitions to solve the problem. Think about a point on the
\n" ); document.write( "y-axis. What would be the x value of such a point. The vertical line along the y-axis corresponds
\n" ); document.write( "to an x-value of 0 ... (think \"go to the point x equals zero and drawing a vertical
\n" ); document.write( "line through that point.
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\n" ); document.write( "So that tells you that in the given equation, you can set x equal to zero and find the
\n" ); document.write( "corresponding value of y by solving for y.
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\n" ); document.write( "The given equation is:
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\n" ); document.write( "5x + 3y -15 = 0
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\n" ); document.write( "Substitute 0 for x to get:
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\n" ); document.write( "5(0) + 3y - 15 = 0
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\n" ); document.write( "Notice that the term 5(0) is zero, so it disappears. Then the equation becomes
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\n" ); document.write( "3y -15 = 0\r
\n" ); document.write( "\n" ); document.write( "Solve this equation by adding 15 to both sides to get:
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\n" ); document.write( "3y = 15
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\n" ); document.write( "Finally, solve for y by dividing both sides by 3 and you have
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\n" ); document.write( "y = 5
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\n" ); document.write( "Now you know that when x = 0, then y = 5. So the ordered pair that identifies the y-intercept
\n" ); document.write( "is:
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\n" ); document.write( "(0, 5)
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\n" ); document.write( "Just for “fun”, what would the ordered pair be for the x-intercept? By using the same
\n" ); document.write( "logical thinking that we did for the y-axis intercept, you can see that a point on the x-axis
\n" ); document.write( "will have y equal to zero, because that must be the value of y for the horizontal
\n" ); document.write( "line to go down the x-axis.
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\n" ); document.write( "Now you can return to the given equation and set y equal to zero so that you can solve for
\n" ); document.write( "the corresponding value of x on the x-axis:
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\n" ); document.write( "5x + 3(0) -15 = 0
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\n" ); document.write( "But 3(0) equals zero so that term disappears and you are left with
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\n" ); document.write( "5x – 15 = 0
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\n" ); document.write( "Solve by adding 15 to both sides to get:
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\n" ); document.write( "5x = 15
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\n" ); document.write( "Finally, divide both sides by 5 to get that:
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\n" ); document.write( "x = 3
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\n" ); document.write( "So the ordered pair for the x-intercept is (3, 0)
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\n" ); document.write( "Once you understand the basic concept you will be able to solve problems such as these much
\n" ); document.write( "faster. You will learn to say to yourself, “I can find the y-intercept by setting x = 0
\n" ); document.write( "and solving for y.” The ordered pair for the y-intercept will then be (0, y) where y is
\n" ); document.write( "the value you find when x equals zero.
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\n" ); document.write( "Similarly, you will say, “I can find the x-intercept by setting y = 0 and solving the
\n" ); document.write( "equation for x.” The ordered pair for the x-intercept will then be (x, 0) where x is the
\n" ); document.write( "value you find from the equation by setting y equal to zero.
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\n" ); document.write( "Hope this clears up the situation for you. And in summary, the answer to your problem is
\n" ); document.write( "(0, 5)\r
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