Solve: 2 (2 x + 9) = 5 x + 72

which step is wrong

Step 1: 4 x + 18 = 5 x + 72

Step 2: 9 x + 18 = 72

Step 3: 9 x = 54

Step 4: x = 6

Step 2 is wrong because they combined like terms incorrectly. The equation should be: 18 = x + 72. Then, in Step 3, you would get x = - 54.

Step-by-step explanation:

The given equation is a multi-step equation involving the distributive property. You would first complete the distributive property by multiplying each term inside the parenthesis by the outside term. Step 1 of the problem completes this step correctly. The next step in the problem would be to use inverse operations to combine like terms and isolate the variable - whatever you do to one side of the equation, you must do to the other. In this case, we need to subtract 4x from both sides, not add, to get: 4x - 4x + 18 = 5x - 4x + 72. This gives us 18 = x + 72. To solve for x, we need to subtract both sides by 72: 18 - 72 = x + 72 - 72, or x = - 54.