document.write( "Question 1200141: Solve the following inequalities :
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document.write( "a) x^2 - 5x + 4 > 0
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document.write( "b) k(2k-3) < k^2 - 2
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document.write( "c) x^2 - 5x - 14 > 0 \n" );
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Algebra.Com's Answer #834177 by math_tutor2020(3817)![]() ![]() ![]() You can put this solution on YOUR website! \n" ); document.write( "I'll do the first problem to get you started.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Let's solve the associated equation \n" ); document.write( "x^2 - 5x + 4 = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So, \n" ); document.write( "x^2 - 5x + 4 = 0 \n" ); document.write( "(x-1)(x-4) = 0 \n" ); document.write( "x-1 = 0 or x-4 = 0 \n" ); document.write( "x = 1 or x = 4 \n" ); document.write( "The quadratic formula is an alternative pathway.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "The roots of x^2 - 5x + 4 are x = 1 and x = 4\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Draw out a number line to plot 1 and 4 on it.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Label the following regions \n" ); document.write( "A: stuff to the left of 1 \n" ); document.write( "B: stuff between 1 and 4 \n" ); document.write( "C: stuff to the right of 4\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Pick a value from region A. \n" ); document.write( "I'll select x = 0 \n" ); document.write( "Plug it into x^2 - 5x + 4 and simplify to get... \n" ); document.write( "x^2 - 5x + 4 \n" ); document.write( "0^2 - 5*0 + 4 \n" ); document.write( "4 \n" ); document.write( "We arrive at a positive value. \n" ); document.write( "Therefore, x = 0 makes x^2 - 5x + 4 > 0 to be true \n" ); document.write( "Any other value in region A will arrive at this same conclusion. \n" ); document.write( "Region A is part of the solution set.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Now onto region B. \n" ); document.write( "Let's pick x = 2 as a representative value from this region 1 < x < 4 \n" ); document.write( "x^2 - 5x + 4 \n" ); document.write( "2^2 - 5*2 + 4 \n" ); document.write( "4 - 10 + 4 \n" ); document.write( "-2 \n" ); document.write( "The result is negative, which means x^2 - 5x + 4 > 0 would be false for any x value in region B. \n" ); document.write( "Region B is NOT part of the solution set.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Lastly region C, which is x > 4 \n" ); document.write( "Let's pick x = 5 \n" ); document.write( "x^2 - 5x + 4 \n" ); document.write( "5^2 - 5*5 + 4 \n" ); document.write( "25 - 25 + 4 \n" ); document.write( "4 \n" ); document.write( "Like with region A, we get a positive result to show x^2 - 5x + 4 > 0 would be true for x values in this interval. \n" ); document.write( "Region C is part of the solution set.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "We found that \n" ); document.write( "Region A, x < 1, is part of the solution set \n" ); document.write( "Region C, x > 4, is also part of the solution set\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Collectively the entire solution set is x < 1 or x > 4 \n" ); document.write( "We can write this in interval notation to get (-infinity, 1) U (4 < infinity) \n" ); document.write( "The U symbol is the union operator. It glues together the two intervals in an \"or\" fashion. \n" ); document.write( "We are either in the interval (-infinity, 1) OR we are in the interval (4 < infinity). We cannot be in both intervals at the same time.\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Answer as inequalities: x < 1 or x > 4 \n" ); document.write( "Answer as interval notation: (-infinity, 1) U (4 < infinity)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Similar question is found here \n" ); document.write( "https://www.algebra.com/algebra/homework/Inequalities/Inequalities.faq.question.1200712.html \n" ); document.write( " \n" ); document.write( " |