Elementary Algebra and Geometry
Section 1.5: Solutions of Systems of Linear Equations
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Solving systems of equations
Ex.1 (#12) Solve the system of equations
1. Substitution method
2. Elimination method
3. Equating two equations: can use only if both equations
are given in the form of either y = … or
x = …
Ex.2 (#16) Solve the system of equations
Ex.3 (#22) Solve the system of equations
Three equations in three variables
* Left-to-right elimination method (will be discussed when
we study chapter 3)
* Substitution method
Ex.4 (#32) Solve the system of equations
Ex.5 (#37) One safe investment pays 10% per year, and a more risky investment pays 18% per year. A
woman who has $145,600 to invest would like to have an income of $20,000 per year from her investments.
How much should she invest at each rate?
Ex.6 (#44) A biologist has a 40% solution and a 10%
solution of the same plant nutrient. How many cubic
centimeters of each solution should be mixed to obtain 25 cc of a 28% solution?