Question

Will is asked to simplify the expression below. 7x - 2(x + 3y) + 3y He states that the simplified expression is 5x + 9y because using the distributive property yields 7x - 2x + 6y + 3y and then combining like terms yields 5x + 9y. 1. What is the error in Will's reasoning? 2. Write the correct simplified expression for 7x - 2(x + 3y) + 3y

Answer 1

Answer: See explanation

Explanation:

7x - 2(x + 3y) + 3y

= 7x - 2x - 6y + 3y

= 5x - 3y

Will got 5x + 9y because he didn't multiply the values in the bracket by the minus sign outside the bracket. He multiplied the values by +2 rather than -2. This resulted in the wrong answer that he got.