Use linear combinations to solve the system
-3x+7y=-42
3x+5y=6
Find Y, then find X

Question

Use linear combinations to solve the system
-3x+7y=-42
  3x+5y=6
Find Y, then find X

anonymous · Answer

attachment

kidrah69 · Answer

-3x+7y=-42
  3x+5y=6
This is called elimination
what is -3+3?

anonymous · Answer

0

kidrah69 · Answer

7+5?

anonymous · Answer

wait, what do you mean by elimination?

kidrah69 · Answer

anonymous · Answer

oh ok, so it would be      0*x + 12y =-36

perl · Answer

$$\large
x \begin{bmatrix}
3 \ -3 \end{bmatrix}  + 
y 
\begin{bmatrix}
7 \ 5 \end{bmatrix} = \begin{bmatrix}
-42 \ 6 \end{bmatrix}

$$

perl · Answer

if you want to use 'linear combinations'

anonymous · Answer

and then   y = 3

anonymous · Answer

wow... I have never heard of that type of computation before

anonymous · Answer

not with this format.

anonymous · Answer

so how would you find x now that we know y=3

perl · Answer

the easiest way to solve it is using elimination, as pooja (kidrah) suggested

anonymous · Answer

oh ok, got it.

perl · Answer

to find x , you can back substitute

anonymous · Answer

does it matter which equation is subsitute y back into?

anonymous · Answer

oh ok. I get the same answer either way.

perl · Answer

right :)