Question

-3x-5y=9 5x + 5y=-15

Answer 1

Hello from MrBillDoesMath!

Answer:

x = -3, y = 0

Discussion:

5x + 5y = -15  =>

x + y = -3        =>           (divide both sides by 5)

x + y - y = -3 -y    =>      (subtract y from both sides)

x = -3 - y  

Substitute x = -3 - y   into the top equation:

-3x - 5y = -9 =>

-3(-3-y) - 5y = 9  =>          ( substitute -3 -y for x)    

(-3)(-3) + (-3)(-y) - 5y  = 9 =>

9    + 3y - 5y = 9            =>      (  -*-   is a + number)

9 -2y = 9      =>

9 - 9 -2y  = 9 - 9     =>      (subtract 9 from both sides)

-2y = 0            =>

y = 0

Since x = -3 -y, x = -3 - 0 = =3

Regards,  

MrB

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