SOLUTION: I need help i am a parent trying to help my son with his homework his teacher gave them the answers to the problems and he has to show work i just do not know how to show the work
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Question 596951: I need help i am a parent trying to help my son with his homework his teacher gave them the answers to the problems and he has to show work i just do not know how to show the work if you could please help me it is algebra solving systems of equations by substituting -4x+y=6 -5x-y+21 X=-3 Y=-6 please help thanks Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! solving systems of equations by substituting
Assuming the problem is:
-4x + y = 6
-5x - y = 21
:
Arrange the 1st equation so we can use it for substitution
-4x + y = 6
Add 4x to both sides
y = 4x + 6
:
Now we can substitute (4x+6) for y in the 2nd equation
-5x - y = 21
-5x -(4x+6) = 21
-5x - 4x - 6 = 21
-9x = 21 + 6
-9x = 27
divide both sides by -9
x = -3
:
Find y using the equation y = 4x + 6, replace x wtih -3
y = 4(-3) + 6
y = -12 + 6
y = -6
:
:
Check your solutions in the 2nd equation
-5(-3) - (-6) = 21
15 + 6 = 21; minus a minus is a plus
