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Homework Quiz 9 Answers

Homework Quiz 9 Answers

Q Math 30 Homework Quiz 9 Answers 1. D. (0, 1) Solve the system x + 4y = 4, 3x - 5y = -5 by the substitution method or addition method. 2. A. (5, -2) Solve the system 3x + y = 13, 2x + 9y = -8 by the substitution method or addition method. 3. D. (-2, -1, 3) Solve the system of equations x - y + z = 2, x + y + z = 0, x + y - z = -6. 4. C. $120,000 at 9% and $80,000 at 8% You invest a total of $200,000 for one year, part at 9% interest and part at 8% interest. The total annual interest is $17,200. How much was invested at each interest rate?

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1.x + 4y = 4 x = 4 – 4y 3(4 – 4y) – 5y = -5 12 – 12y – 5y = -5 12 – 17y = -5 -17y = -5 – 12 -17y = -17 y = 1 x + 4(1) = 4 x + 4 = 4 x = 0 2.3x + y = 13 y = 13 – 3x 2x + 9y = -8 2x + 9(13 – 3x) = -8 2x + 117 – 27x = -8 -25x + 117 = -8 117 + 8 = 25x 125 = 25x x = 5