document.write( "Question 1164498: (i)Use the definition of absolute value to solve each equation,
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\n" ); document.write( "|-1/5 - 1/2k| = 9/5
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Algebra.Com's Answer #789021 by Theo(13342)\"\" \"About 
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definition of absolute value.\r
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\n" ); document.write( "\n" ); document.write( "absolute value of x if x is positive and absolute value of x is -x if x is negative.\r
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\n" ); document.write( "\n" ); document.write( "the absolute value of an expression is always positive.\r
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\n" ); document.write( "\n" ); document.write( "your problem states that |-1/5 - 1/2 * k| = 9/5\r
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\n" ); document.write( "\n" ); document.write( "by the definition, when the expression is positive it is equal to 9/5 and when the expression is negative, then minus the expression is equal to 9/5.\r
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\n" ); document.write( "\n" ); document.write( "therefore:\r
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\n" ); document.write( "\n" ); document.write( "when the expression is positive, you get:\r
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\n" ); document.write( "\n" ); document.write( "(-1/5 - 1/2 * k) = 9/5
\n" ); document.write( "this becomes -1/5 - 1/2 * k = 9/5
\n" ); document.write( "add 1/5 to both sides of the equation and simplify to get:
\n" ); document.write( "-1/2 * k = 10/5
\n" ); document.write( "solve for k to get:
\n" ); document.write( "k = -20/5 = -4
\n" ); document.write( "confirm by replacing k in the original equation to get:
\n" ); document.write( "|-1/5 - 1/2 * k| = 9/5
\n" ); document.write( "this becomes |9/5| = 9/5 which becomes 9/5 = 9/5, confirming the value of k is correct.\r
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\n" ); document.write( "\n" ); document.write( "when the expression is negative, you get:\r
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\n" ); document.write( "\n" ); document.write( "-(-1/5 - 1/2 * k) = 9/5
\n" ); document.write( "this becomes 1/5 + 1/2 * k = 9/5
\n" ); document.write( "subtract 1/5 from both sides of the equation and simplify to get:
\n" ); document.write( "1/2 * k = 8/5
\n" ); document.write( "solve for k to get:
\n" ); document.write( "k = 16/5 = 3.2
\n" ); document.write( "confirm by replacing k in the original equation to get:
\n" ); document.write( "|-1/5 - 1/2 * 16/5| = 9/5 which becomes |-1/5 - 8/5| = 9/5 which becomes |-9/5| = 9/5 which becomes 9/5 = 9/5, confirming the value of k is good.\r
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\n" ); document.write( "\n" ); document.write( "you can graph two equations as shown below:\r
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\n" ); document.write( "\n" ); document.write( "y = |-1/5 - 1/2 * x| and y = 9/5\r
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\n" ); document.write( "\n" ); document.write( "the intersection of the two equations is the solution.
\n" ); document.write( "that solution is x = -4 and x = 3.2
\n" ); document.write( "x = 3.2 is the same as x = 16/5.\r
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\n" ); document.write( "\n" ); document.write( "you can also graph one equation as shown below:\r
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\n" ); document.write( "\n" ); document.write( "y - |-1/5 - 1/2 * x| - y = 9/5
\n" ); document.write( "the intersection of the equation with the x-axis is the solution.\r
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\n" ); document.write( "\n" ); document.write( "the graph of both solutions is shown below:\r
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\n" ); document.write( "\n" ); document.write( "you can see that the x-coordinate of both graphs are the same.
\n" ); document.write( "those are your solutions.
\n" ); document.write( "the y-coordinates will be different because the second graph is shifted down 9/5 units of y.\r
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\n" ); document.write( "\n" ); document.write( "y = 9/5 is the same as y = 1.8.\r
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