Diana187
contestada

will mark brainliest!!
solve this system of linear equations. separate the x- and y- values with a coma. 9x=27-9y
20x=71-9y

Respuesta :

altavistard
Solve the system

9x = 27-9y
20x=71-9y

Let's use the "elimination through addition/subtraction method.
Multiply the first equation by -1 so as to obtain +9y:

-9x = -27 + 9y
20x=  71-   9y
--------------------

Add these 2 equations together:

-9x = -27 + 9y
20x=  71-   9y
--------------------
 11x = 44

Solve this for x:  x = 44/11 = 4.

Now find y by subst. 4 for x in either of the original equations.

Using the second equation:     

20x=71-9y
20(4) = 71 - 9y
80-71 = -9y
9 = -9y.  Then y = -1.

The solution set is (4,-1).

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