document.write( "Question 71110: 3x + 7 = x^2 + k = 7x + 15 \r
\n" ); document.write( "\n" ); document.write( "What is the value of k? \n" ); document.write( "
Algebra.Com's Answer #50893 by ankor@dixie-net.com(22740)\"\" \"About 
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3x + 7 = x^2 + k = 7x + 15
\n" ); document.write( "What is the value of k?
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\n" ); document.write( "Two equations
\n" ); document.write( "Solve the one without the k
\n" ); document.write( "3x + 7 = 7x + 15
\n" ); document.write( "3x - 7x = 15 - 7
\n" ); document.write( "-4x = 8
\n" ); document.write( "x = 8/-4
\n" ); document.write( "x = -2
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\n" ); document.write( "The equation with the k
\n" ); document.write( " x^2 + k = 7x + 15
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\n" ); document.write( "Substitute -2 for x and find k:
\n" ); document.write( "(-2)^2 + k = 7(-2) + 15
\n" ); document.write( "4 + k = -14 + 15
\n" ); document.write( "4 + k = +1
\n" ); document.write( "k = 1 - 4
\n" ); document.write( "k = -3
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\n" ); document.write( "Check: Substitute values for x and k in the original problem:
\n" ); document.write( "3x + 7 = x^2 + k = 7x + 15
\n" ); document.write( "3(-2) + 7 = (-2)^2 + -3 = 7(-2) + 15
\n" ); document.write( "-6 + 7 = 4 - 3 = -14 + 15; checks out
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