please help!

[jenzy569]

1. Solve by substitution or elimination method:

3x – 2y = 26
-7x + 3y = -49

2. Solve by substitution or elimination method:

4x – 5y = 14
-12x + 15y = -42

3. Solve by substitution or elimination method:

-2x + 6y = 19
10x – 30y = -15


Second part of problems:


1. Plot the graph of the equations 2x - 3y = 5 and 4x - 6y = 21 and interpret the result.
2. Plot the graph of the equations 4x - 6y = 12 and x - 5y = 10 and interpret the result.
3. Plot the graph of the equations 8x - 4y = 12 and -4x + 2y = -6 and interpret the result.

 

[Deleted member 4993]

1. Solve by substitution or elimination method:

3x – 2y = 26
-7x + 3y = -49

2. Solve by substitution or elimination method:

4x – 5y = 14
-12x + 15y = -42

3. Solve by substitution or elimination method:

-2x + 6y = 19
10x – 30y = -15


Second part of problems:


1. Plot the graph of the equations 2x - 3y = 5 and 4x - 6y = 21 and interpret the result.
2. Plot the graph of the equations 4x - 6y = 12 and x - 5y = 10 and interpret the result.
3. Plot the graph of the equations 8x - 4y = 12 and -4x + 2y = -6 and interpret the result.

DUPLICATE POST:

viewtopic.php?f=9&t=35272

 

[fasteddie65]

1. Solve by substitution or elimination method:

[3x – 2y = 26] • 3
[-7x + 3y = -49] • 2

9x - 6y = 78
-14x + 6y = -98

Adding: -5x = -20, so x = 4. Now substitute that in for x in either equation and find y.

2. Solve by substitution or elimination method:

4x – 5y = 14
-12x + 15y = -42

Here, notice that -5 • 3 = -15, so multiply the first equation by 3 and add it to the second.

3. Solve by substitution or elimination method:

-2x + 6y = 19
10x – 30y = -15

For this one, notice that 5 • 6 = 30, so multiply the first equation by 5 and add it to the second.


Second part of problems:


1. Plot the graph of the equations 2x - 3y = 5 and 4x - 6y = 21 and interpret the result.

Notice that the slope of the first equation is 2/3 and that of the second is 4/6 = 2/3. The lines are parallel, so there is no solution.

2. Plot the graph of the equations 4x - 6y = 12 and x - 5y = 10 and interpret the result.

The lines intersect at (-2, 0) so the solution of the system is x = -2 and y = 0.

3. Plot the graph of the equations 8x - 4y = 12 and -4x + 2y = -6 and interpret the result.

The graphs coincide, i.e. they are the same line. The solution is {(x,y)| 8x - 4y = 12}, in other words an infinite number of points, all of which lie on the line.