document.write( "Question 1058494: Three times a number is greater than or equal to 12 and less than 21 \n" ); document.write( "
Algebra.Com's Answer #673622 by solve_for_x(190)![]() ![]() ![]() You can put this solution on YOUR website! Let x represent the unknown number.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Three times that number is then represented as 3x.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Since this value must be \"greater than or equal to 12, and less than 21\", \n" ); document.write( "you can write:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "12 ≤ 3x < 21\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Dividing through by 3 leaves:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "12 / 3 ≤ 3x / 3 < 21 / 3\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "4 ≤ x < 7\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Solution: The number must be greater than or equal to 4, and less than 7.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "In interval notation, the solution is [4, 7). \n" ); document.write( " |