document.write( "Question 576060: Are the following two lines parallel? 3x + 4y = 4 2x - 6y = 7 \n" ); document.write( "
Algebra.Com's Answer #369715 by bucky(2189) ![]() You can put this solution on YOUR website! In order to be parallel, the graphs of each of these two equations must have the same slope. \n" ); document.write( ". \n" ); document.write( "To find the slopes, let's convert each equation to the slope intercept form. That form is: \n" ); document.write( ". \n" ); document.write( "y = mx + b \n" ); document.write( ". \n" ); document.write( "and m, which is the multiplier of x, is the slope of the graph. (b is the value at which the graph crosses the y-axis.) \n" ); document.write( ". \n" ); document.write( "So let's look at the first equation and let's solve it for y. \n" ); document.write( ". \n" ); document.write( "Start with: \n" ); document.write( ". \n" ); document.write( "3x + 4y = 4 \n" ); document.write( ". \n" ); document.write( "Get rid of the 3x on the left side by subtracting 3x from both sides. With that subtraction the equation becomes: \n" ); document.write( ". \n" ); document.write( "4y = -3x + 4 \n" ); document.write( ". \n" ); document.write( "Now solve for y by dividing both sides of this equation (all terms) by 4. This results in: \n" ); document.write( ". \n" ); document.write( "y = (-3/4)x + 4/4 \n" ); document.write( ". \n" ); document.write( "and the 4/4 results in 1, so the equation becomes: \n" ); document.write( ". \n" ); document.write( "y = (-3/4)x + 1 \n" ); document.write( ". \n" ); document.write( "By comparing this to the slope intercept form you can see that m, the slope, is the multiplier of x and it is -3/4. \n" ); document.write( ". \n" ); document.write( "Now, lets do the same thing for the second equation. \n" ); document.write( ". \n" ); document.write( "Start with: \n" ); document.write( ". \n" ); document.write( "2x - 6y = 7 \n" ); document.write( ". \n" ); document.write( "Get rid of the 2x on the left side by subtracting 2x from both sides to get: \n" ); document.write( ". \n" ); document.write( "-6y = -2x + 7 \n" ); document.write( ". \n" ); document.write( "Solve for y by dividing both sides (all terms) by -6 and the equation becomes: \n" ); document.write( ". \n" ); document.write( "y = (-2/-6)x + 7/(-6) \n" ); document.write( ". \n" ); document.write( "This time the multiplier of the x is (-2/-6) which reduces to +1/3. ( b is equal to -7/6) \n" ); document.write( ". \n" ); document.write( "So for one equation we have the slope equal to -3/2 and for the other equation the slope is +1/3. The two slopes are not the same. Therefore, the graphs have to cross somewhere. And since they cross at some point they are not parallel. \n" ); document.write( ". \n" ); document.write( "You now have the answer and there is nothing else that you need to do. \n" ); document.write( ". \n" ); document.write( "Hope this helps you to understand the problem. \n" ); document.write( ". \n" ); document.write( " |