Question

Which of the following would not be the result of a substitution in the following system?

2x + y = 7
y - x= 1

A. 7 - 2x- x = 1

B. 2x + x + 1 = 7

C. 2(y + 1) + y = 7​

Answer 1

C. 2(y + 1) + y = 7​

Explanation:

Answer 2

Hello!

The correct option is:

C.
`2(y+1)+y=7`

Why?

To find which of the given options are not the result of a substitution in the given system, we need to isolate the variable in function of the other variable, and then substitute it.

So, substituting and discarding, we have:

- First equation:

`2x+y=7`

Isolating "y", we have:

`y=7-2x`

Then, substituting it into the second equation, we have:

`y-x=1`

`7-2x-x=1`

We have that it's a result of a substitutiong in the following system (option A)

- Second equation:

`y-x=1`

Isolating "y", we have:

`y=x+1`

Then, substituting it into the first equation, we have:

`2x+y=7`

.

So, the correct option is:

C. [tex]2(y+1)+y=7" src="

Have a nice day!