Woody's Substitution

Don't Get Down If You Don't Know How To Use Substitution...
Woody Will Always Come To The Rescue!

Why Substitution?
The Substitution method is a useful technique for solving systems in which a variable has a coefficient of 1!

Equations:

2x + y = 6
3x + 4y = 4

<>Work:
We solve the first equation for y because it's y-term has a coefficient of 1.
y = 6 - 2x
We can now substitute 6 - 2x for y in the second equation.
3x + 4y = 4
3x + 4(6-2x) = 4
This gives us an equation in one variable.
We can now solve for x.
3x + 24 - 8x = 4
-5x = -20
x = 4
Now we can substitute 4 for x in either equation and solve for y.
2x + y = 6
2(4) + y = 6
8 + y = 6
y = -2
Final Point: (4, -2)

Now We Can Check Our Answer By Substituting
x and y in either equation.
2x + y = 6
2(4) + -2 = 6
8 - 2 = 6
6 = 6
Correct!

Here Are 5 Practice Problems!

Equations:	Correct Answer:
1. y = 5 - 4x 3x - 2y = 12	(2 , -3)
2. 3x - 4y = -15 5x + y = -2	(-1 , 3)
3. x = 3 - 3y 4y = x + 11	(-3 , 2)
4. 2x + y = -6 3x + y = -10	(-4 , 2)
5. y = -x + 6 x - 2y = -6	(2 , 4)

Back To Home Page