Question

Kelsey solved the following equation:

Answer 1

9514 1404 393

Answer:

  (a) 1. Distributive property 2. Combine like terms 3. Addition property of equality 4. Division property of equality

Step-by-step explanation:

Replacement of -1/2(8x +2) by -4x -1 is use of the distributive property, eliminating choices B and D.

In step 3, addition of 1 to both sides of the equation is use of the addition property of equality, eliminating choice C. This leaves only choice A.

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Additional comment

This problem makes a distinction between the addition property of equality and the subtraction property of equality. They are essentially the same property, since addition of +1 is the same as subtraction of -1. The result shown in Step 3 could be from addition of +1 to both sides of the equation, or it could be from subtraction of -1 from both sides of the equation.

In general, you want to add the opposite of the number you don't want. Here, that number is -1, so we add +1. Of course, adding an opposite is the same as subtracting.

In short, you can argue both choices A and C have correct justifications. The only reason to prefer choice A is that we usually think of adding positive numbers as addition, and adding negative numbers as subtraction.