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Mathematics 9 Online
OpenStudy (piercetheveil47):

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OpenStudy (solomonzelman):

first equation times -2 and add them

OpenStudy (piercetheveil47):

what exactly does that mean?

OpenStudy (solomonzelman):

multiply every term in the first equation times 2 (that is what I mean by "multiply the first equation times -2") after doing so, add the equations together.

OpenStudy (piercetheveil47):

so like this:

OpenStudy (piercetheveil47):

3 times -2 - 2y = 6?

OpenStudy (solomonzelman):

\(\large\color{black}{ \displaystyle \color{red}{(}3x - 2y = 6\color{red}{)\times (-2)} }\) \(\large\color{black}{ \displaystyle \color{red}{ (-2)}3x - \color{red}{ (-2)}2y = \color{red}{ (-2)}6 }\) \(\large\color{black}{ \displaystyle -6x +4y = -12 }\)

OpenStudy (solomonzelman):

this is how I multiply the equation times -2, I take each term in it and multiply times -2.

OpenStudy (solomonzelman):

is this making some sense ?

OpenStudy (piercetheveil47):

ohhhhhh

OpenStudy (piercetheveil47):

yeah it makes sense now

OpenStudy (solomonzelman):

yes, so your system of equations NOW, is: \(\large\color{blue}{ \displaystyle -6x +4y = -12 }\) \(\large\color{black}{ \displaystyle 6x - 4y = 14 }\) (In blue I posted your new 1st equation, that results after multiplying it times -2)

OpenStudy (solomonzelman):

Now, do elimination (add these equations together)

OpenStudy (piercetheveil47):

okay this may take a min

OpenStudy (solomonzelman):

take your time

OpenStudy (piercetheveil47):

i got 0x - 0y = 2

OpenStudy (solomonzelman):

yes, that means that you got 0=2

OpenStudy (solomonzelman):

Is it correct that THIS is what adding the equations together leaves you with?

OpenStudy (piercetheveil47):

yes

OpenStudy (piercetheveil47):

i think

OpenStudy (piercetheveil47):

so would the answer be

OpenStudy (piercetheveil47):

c? idk :/

OpenStudy (solomonzelman):

well, if adding the equations (the elimination) gives you something that is not true under any circumstances.... then ?

OpenStudy (piercetheveil47):

ohhhh so no solutions

OpenStudy (piercetheveil47):

?

OpenStudy (solomonzelman):

yes

OpenStudy (solomonzelman):

no solution, is correct.

OpenStudy (piercetheveil47):

thank you!

OpenStudy (solomonzelman):

Or think of it this way

OpenStudy (solomonzelman):

When you plug in your "x" and "y" into the equation (into 0=2) you still get 0=2, since you aren't really plugging anything in (why? because x and y are not present in the equation) and that means that regardless of what value you choose for x and for y, the statement (statement 0=2) will never be true.

OpenStudy (solomonzelman):

and that means that since there are no values of x and y that satisfy the statement 0=2, therefore there is no solution for x and for y.

OpenStudy (piercetheveil47):

ohhhhhhhhh!! that actually makes a lot of sense. thank you

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