Solve the simultaneous equations 1x + 1y = 9 and 3x - 1y = 3. What is x + y?
Answer and explanation
Correct answer: D. 9
- Step 1: Eliminate one unknown by adding or subtracting suitable multiples of the equations.
- Step 2: The solution is x = 3, y = 6, so x + y = 9.
Answer
9.
Why not the others: 3: only x was given. 6: only y was given. -3: the values were subtracted instead of added.
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