document.write( "Question 443624: Write the slope-intercept equation for the line that passes through (-7, 6) and is perpendicular to -7x + 9y = -2 Please show all of your work. \n" ); document.write( "

Algebra.Com's Answer #853312 by ikleyn(53431) $\"\"$ $\"About$

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\n" ); document.write( "Write the slope-intercept equation for the line that passes through (-7, 6) and is perpendicular to -7x + 9y = -2
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\n" ); document.write( "\n" ); document.write( "        Strictly saying, the solution and the answer in the post by @mananth are incorrect.\r
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\n" ); document.write( "\n" ); document.write( "        Indeed, if I substitute coordinates (-7,6) into his equation y = -1.29x-3, \r
\n" ); document.write( "\n" ); document.write( "        I will get y = -1.29*(-7) + 6 = 6.03, but not precisely 6,\r
\n" ); document.write( "\n" ); document.write( "        which means that the point (-7,6) does not lie on the line.\r
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\n" ); document.write( "\n" ); document.write( "        In this my post, I will present a correct precise solution and the correct answer, and then will explain, \r
\n" ); document.write( "\n" ); document.write( "        WHY the solution by @mananth is wrong.\r
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document.write( "Any line perpendicular to the given line -7x + 9y = -2  has an equation of the form\r\n" );
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document.write( "    7y + 9x = c   (1)\r\n" );
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document.write( "where 'c' is some real constant.  So, we only need to find the value of 'c'.\r\n" );
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document.write( "To do it, we substitute the coordinates of the given point (-7,6) into equation (1)\r\n" );
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document.write( "    7*6 + 9*(-7) = 42 - 63 = -21.\r\n" );
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document.write( "So, the sough equation is\r\n" );
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document.write( "    7y + 9x = -21.\r\n" );
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document.write( "It is NOT that equation, which is presented as the answer in the post by @mananth.\r\n" );
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\n" ); document.write( "\n" ); document.write( "So, I solved the problem correctly, and my answer is different from that by @mananth.\r
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\n" ); document.write( "\n" ); document.write( "The error made by @mananth, is that he replaced the precise value m1 = $\"7%2F9\"$ of the slope
\n" ); document.write( "of the original line by the decimal value 0.78.\r
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\n" ); document.write( "\n" ); document.write( "This value, 0.78, is only approximation, but not the precise rational value.\r
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\n" ); document.write( "\n" ); document.write( "So, the error by @mananth is that he uses his computer code in the form, which IS NOT APPLICABLE
\n" ); document.write( "and IS NOT ADEQUATE to the problem.\r
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