What’s the answer to all of these ?

Answers:

So the solution is (x,y) = (4, -1)

Work Shown:

6x + 7y = 17

6x + 7( y ) = 17

6x + 7( -3x+11 ) = 17 ... replace every copy of y with -3x+11

6x - 21x + 77 = 17

-15x = 17-77

-15x = -60

x = -60/(-15)

x = 4

We'll use this x value to find y

y = -3x+11

y = -3(4)+11 ... replace x with 4

y = -12+11

y = -1

We have  x = 4 and y = -1 pair up together to give us the solution (x,y) = (4, -1)

To check the solution, we plug x = 4 and y = -1 into each equation

Plugging the values into the first equation leads to...

y = -3x+11

-1 = -3(4)+11

-1 = -1

This is effectively already done in the last part of the previous section. But it doesn't hurt to verify like this regardless.

We'll need to verify the second equation as well.

6x + 7y = 17

6(4) + 7(-1) = 17

24 - 7 = 17

17 = 17

We get a true equation, so the solution is confirmed with both equations. Overall, the solution to the system of equations is confirmed. This system is independent and consistent.