nAlgebra 1 7.2 Solving a System of Linear Equations using Substitution
A. Substitution method – one equation is solved in terms of a variable and then that expression is plugged in for or substituted into the second equation for that variable.
Substitution Method
1. ___________ one of the equations for one of its variables
2. _______________ this expression into the other equation and solve for its variable
3. ____________ this value into one of the original equations and solve
4. ___________ the solution in each original.
5. Write the solution as an _________ ________ in alphabetical order.
Oct 29­3:00 PM
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B. Solve the following systems and indicate whether it is consistent or inconsistent.
1. y = 3x ‐ 4
y = 4 + x
3. a – b = 2
‐2a + 3b = 3
2. 4c + 2d = 10
c = ‐3d + 10
4. 3g – 2h = ‐1
4g + h = 17
Oct 29­3:01 PM
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5. 2j – 3k = 3
j + k = 14
7. x – y = 4
2y = 2x – 8
6. 2r + s = 11
6r – 2s = ‐2
8. 6y + 8x = 28
3 = 2x ‐ y
Oct 29­3:04 PM
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C. Applications:
10. A veterinarian needs 60 pounds of dog food that is 15% protein. He will combine a beef mix that is 18% protein with a bacon mix that is 9% protein. How many pounds of each does he need to make the 15% protein mix?
11. A youth group with 26 members is going to the beach. In addition, there will be 5 chaperones that will drive the kids in either a car or a van. Each van seats 7 and each car seats 5. How many vans and cars will be needed?
Oct 29­3:06 PM
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7.2 HW p. 384 #s 1 ­ 21 all
Feb 15­8:32 AM
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