document.write( "Question 1071816: what is the answer of |3x+4|+|2x+1|+|x+1|=12 \n" ); document.write( "
Algebra.Com's Answer #686723 by Theo(13342) You can put this solution on YOUR website! well, one of the answers is 1. \n" ); document.write( "you just take away the positive value sign and solve for x and you get 1. \n" ); document.write( "the expression inside the positive value sign can be negative. \n" ); document.write( "you would get -(x + 1) - (3x+4) - (2x+1) - (x+1) = 12 \n" ); document.write( "that becomes: \n" ); document.write( "- 3x - 4 - 2x - 1 - x - 1 = 12 \n" ); document.write( "combine like terms to get: -6x - 6 = 12 \n" ); document.write( "add 6 to both sides to get -6x = 18 \n" ); document.write( "solve for x to get x = -3\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "so, if i did this right, x = 1 or x = -3.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you can also solve it graphically.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your graph would look like this.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \r\n" ); document.write( " \n" ); document.write( "\n" ); document.write( "abs(x) means the same thing as |x| to this graphing software.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the main idea is that if the absolute value of an expression is equal to something, then either that expression is equal to that something or that expression times -1 is equal to that something.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "for example:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "abs(3x+4) = 7\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "either (3x+4) = 7 or -(3x+4) = 7\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "this gets you x = 1 or x = -11/3\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the books will usually show you that:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "abs(x) = x and abs (x) = -x\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "what they are talking about is the expression inside the absolute value sign, an not just the value of x.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "therefore:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "abs(x + a) = x + a and abs(x) = -(x + a).\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "i used that fact to solve this problem.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the expression inside the absolute value sign will either be positive or it will be negative.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you will also see:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "if abs(x+a) > y, then (x+a) > y and (x+a) < -y.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "this also stems from what i just told you.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "in my interpretation:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "(x+a) > y and -(x+a) > y\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "in the second inequality, just multiply both sides of the inequality by -1 and you will get (x+a) < -y\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the books have done that extra step for you but do not usually explain why it is that way.\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |