AlgebraHardValue of a combination from a system
Algebra practice question
The solution (x, y) of the system 2x + 3y = 19 and 5x − y = 22 also satisfies 4x − 3y = n. What is the value of n?
Answer: 11
From the second equation y = 5x − 22; substituting, 2x + 15x − 66 = 19 gives x = 5 and y = 3. Then n = 4(5) − 3(3) = 11.
Common wrong answers
- If you answered 2
- 2 is x − y; evaluate 4x − 3y with x = 5, y = 3.
- If you answered 8
- 8 is x + y; the asked combination is 4x − 3y = 11.
- If you answered 29
- 29 is 4x + 3y; the expression subtracts 3y: 20 − 9 = 11.
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