A student solved the
equation X + 2 (X + 1) = 17
below and showed their work in the table below.
Problem x + 2(X + 1) = 17
Line 1.2 + 2x + 2 = 17
Line 2. 3x + 2 = 17
Line 3. 3x = 15
Line 4. 2 = 45
Identify the property used to arrive at Line 1.
Identify the property used to arrive at Line 2.
What line has a mistake?
What should have been the correct answer for that line?
The property used to arrive at Line 1 is the distributive property, as the student multiplied 2 to both terms inside the parentheses.
The property used to arrive at Line 2 is combining like terms, as the student combined 2x and 2 on the left side of the equation.
Line 4 has a mistake. The correct equation would be 3x = 15, not 2 = 45. The student made an error in simplifying 3x = 15 to 2 = 45. The correct answer for Line 4 should be x = 5.