solve by substitution method
y=x-4
6x-9y=21
-x+y=-4
6x-9y=21
multiply the top row by 6
-6x+6y=-24
6x-9y=21
-3y=-3
y=1
put 1 back in either equation for y
i put it in the first one
1=x-4
x=5
Oh sorry, i just realized it said to use substitution and I used elimination. I forgot how to do substitution.
just sub in the first equation into the second
6x - 9y = 21
6x - 9(x-4) = 21
6x - 9x + 36 = 21
-3x = -15
x = 5
then y = 5-4 = 1
-2x+4y=-4 and 6x + 6y = -24
To solve the given system of equations using the substitution method, we will solve one equation for one variable and substitute it into the other equation. Let's start solving for y in the first equation.
1) y = x - 4
Now, substitute this expression for y in the second equation.
2) 6x - 9y = 21
Substitute y with (x - 4) from equation 1:
6x - 9(x - 4) = 21
Now, distribute the -9:
6x - 9x + 36 = 21
Combine like terms:
-3x + 36 = 21
Now, isolate the variable x by subtracting 36 from both sides:
-3x = 21 - 36
-3x = -15
Next, divide both sides by -3 to solve for x:
x = -15 / -3
x = 5
Now that we have found x, substitute it back into equation 1 to find y:
y = x - 4
y = 5 - 4
y = 1
So the solution to the system of equations is x = 5 and y = 1.