document.write( "Question 1199000: Solve for x the inequality equation (x+9)/(x+1) -2 > 0\r
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document.write( "The correct answer is one of the following. Which one is correct?\r
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document.write( "A) -1 < x < 7\r
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document.write( "B) x > 7\r
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document.write( "C) -1 < x < 8\r
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document.write( "D) x > 8 \n" );
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Algebra.Com's Answer #832692 by math_tutor2020(3817)![]() ![]() ![]() You can put this solution on YOUR website! \n" ); document.write( "As the tutor @greenestamps has shown \n" ); document.write( " \n" ); document.write( "simplifies to \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "If x = 7, then the numerator is 0. \n" ); document.write( "If x = -1, then the denominator is 0, so we must avoid this x value.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Draw a number line with -1 and 7 marked on it. \n" ); document.write( "Label the following regions or intervals \n" ); document.write( "P: -infinity < x < -1 \n" ); document.write( "Q: -1 < x < 7 \n" ); document.write( "R: 7 < x < infinity \n" ); document.write( " \n" ); document.write( "Note the open holes at -1 and 7.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Let's select an x value from interval P (shown in red above) \n" ); document.write( "I'll pick x = -2 \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( "which is false, so x = -2 is not a solution to the inequality. \n" ); document.write( "By extension any item in interval P will also be non-solutions. \n" ); document.write( "This rules out interval P from the solution set.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Now pick something from interval Q. \n" ); document.write( "I'll go for x = 0 \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( "which is true. \n" ); document.write( "You should find similar true results for any other value in interval Q. \n" ); document.write( "So interval Q is part of the answer.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Lastly, we need to check interval R. \n" ); document.write( "Let's say we select x = 8 \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( "Like with interval P, we get a false statement \n" ); document.write( "So anything in interval R leads to a false statement.\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Therefore, the only valid solution set is -1 < x < 7 \n" ); document.write( "Which in interval notation would be (-1,7) \n" ); document.write( "Be sure not to mix this up with ordered pair notation.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Confirmation can be done using a graph. \n" ); document.write( "Desmos or GeoGebra are good free graphing tools. \n" ); document.write( " \n" ); document.write( "The green curve represents y = (x+9)/(x+1) -2 aka y = (-x+7)/(x+1) \n" ); document.write( "This green curve is above the x axis on the interval -1 < x < 7 \n" ); document.write( "It is below the x axis when either x < -1 or when x > 7. \n" ); document.write( "The x intercept is 7, and there's a vertical asymptote at x = -1.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "-------------------------------------------------------\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Answer: Choice A) -1 < x < 7 \n" ); document.write( " \n" ); document.write( " |