document.write( "Question 77017: 7(x – 3) > 5x - 14 \n" ); document.write( "
Algebra.Com's Answer #55232 by bucky(2189)![]() ![]() ![]() You can put this solution on YOUR website! 7(x – 3) > 5x - 14 \n" ); document.write( ". \n" ); document.write( "The object of solving an inequality is to solve for x. \n" ); document.write( ". \n" ); document.write( "You can treat these problems about the same as an equation with one exception. That \n" ); document.write( "exception is that if you divide or multiply both sides of the inequality by a negative \n" ); document.write( "number, then you must reverse the direction of the inequality arrow. \n" ); document.write( ". \n" ); document.write( "Let's proceed. First multiply out the left side to get: \n" ); document.write( ". \n" ); document.write( "7x - 21 > 5x - 14 \n" ); document.write( ". \n" ); document.write( "Get rid of the -21 on the left side of the equation by adding +21. But if you add + 21 to \n" ); document.write( "the left side you must also add +21 to the right side. When you do that, the inequality \n" ); document.write( "becomes: \n" ); document.write( ". \n" ); document.write( "7x > 5x + 7 \n" ); document.write( ". \n" ); document.write( "(The +7 comes from -14 + 21.) \n" ); document.write( ". \n" ); document.write( "Now eliminate the 5x on the right side by subtracting 5x from it. But when you subtract \n" ); document.write( "5x from the right side, you must also subtract it from the left side. This causes \n" ); document.write( "the inequality to become: \n" ); document.write( ". \n" ); document.write( "2x > +7 \n" ); document.write( ". \n" ); document.write( "Finally, divide both sides by 2 to solve for +x. That division causes the inequality \n" ); document.write( "to become \n" ); document.write( ". \n" ); document.write( "x > +7/2 or x > +3.5 \n" ); document.write( ". \n" ); document.write( "So x must lie to the right of 3.5 on the number line. \n" ); document.write( ". \n" ); document.write( "Let's spot check. Suppose we let x = +4. Plug that into the original problem and you \n" ); document.write( "get: \n" ); document.write( ". \n" ); document.write( "7(4 – 3) > 5*4 - 14 \n" ); document.write( ". \n" ); document.write( "This simplifies to: \n" ); document.write( ". \n" ); document.write( "7(1) > 20 - 14 \n" ); document.write( ". \n" ); document.write( "Which further simplifies to: \n" ); document.write( ". \n" ); document.write( "7 > 6 \n" ); document.write( ". \n" ); document.write( "That works. Now suppose we let x be a number less that 3.5 ... say x = 3. Plug that \n" ); document.write( "value into the original problem and it becomes: \n" ); document.write( ". \n" ); document.write( "7(3 – 3) > 5*3 - 14 \n" ); document.write( ". \n" ); document.write( "which simplifies to: \n" ); document.write( ". \n" ); document.write( "0 > 15 - 14 or 0 > 1 \n" ); document.write( ". \n" ); document.write( "that does NOT work. So from these couple of spot checks, it appears that our solution \n" ); document.write( "is probably correct. (It is correct ...) \n" ); document.write( ". \n" ); document.write( "Hope this helps you to understand inequalities a little better, and helps you to see that \n" ); document.write( "for the most part you can operate on them just as you would an equation. And don't forget \n" ); document.write( "the rule that if you multiply or divide both sides of an inequality by a negative \n" ); document.write( "quantity, you must reverse the direction of the inequality arrow. We did not need to \n" ); document.write( "apply that rule in this problem. \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( " |