3 = 2 – x 3 = 2 – 2 – x 3 = –x 2003-03-02-00-00_files/i0110000.jpg –3 = x A. The student incorrectly applied the multiplication
property of equality before the addition property of equality. B. The student did not properly apply the addition property of equality to isolate x. C. The student did not properly apply the multiplication property of equality to isolate x. D. The student correctly solved the two-step equation.
Answer: B. The student did not properly apply the addition property to isolate x
Explanation: When given an equation to solve, always remember that when you do an external operation (add/subtract/multiply a term or divide by a term) on one side of the equation, the same operation should be applied on the other side in order to maintain the equality of the equation.
Now, let's take a look on the steps done: Step 1: 3 = 2 - x Step 2: 3 = 2 - 2 - x Step 3: 3 = -x
Now, note n step 2, the student wanted to get rid of the 2 next to the x, therefore, he subtracted 2. However, the student did not subtract the 2 from the other side of the equation. Since we're taking addition (we're adding a -2), therefore, the student incorrectly applied the addition property to isolate the x.
The correct steps would be as follows: Step 1: 3 = 2 - x Step 2: 3 - 2 = 2 - 2 - x Step 3: 1 = - x
