This problem has two parts, Part A and Part B. Read the proof, and then answer both parts.
Given: (a+b)2
Prove (a+b)2=a2+2ab+b2.
Statements Reasons
1. (a+b)2 Given
2. (a+b)(a+b) Rewrite the power as a product of the base.
3. _[blank ]_ Distributive Property
4. a2+ab+ab+b2 Distributive Property
5. a2+2ab+b2 Combine like terms.
Part A: Which statement correctly fills the blank in Statement 3 to complete the proof?
Part B: Which analysis of the proof correctly describes the efficiency of steps?
Select one answer for Part A and select one answer for Part B.
A: a2+ab−ab+b2=a2+2ab+b2
B: Using the distributive property first was unnecessary in Step 3 as it was undone in Step 4.
B: The proof is not efficient because like terms are combined twice.
A: 2a+2b+2ab=a2+2ab+b2
A: a(a+b)+b(a+b)=a2+2ab+b2
B: By focusing on one side of the equation, the process is the most direct path to finalize the proof.
A: b(a+b)+b(a+b)=a2+2ab+b2
Part A: To fill the blank correctly in Statement 3, we need to use the Distributive Property. The Distributive Property states that for any real numbers a, b, and c, the product of a and the sum of b and c can be written as the sum of the product of a and b and the product of a and c.
Therefore, the correct statement to fill the blank in Statement 3 is:
(a+b)(a+b) = a(a+b) + b(a+b)
Part B: The analysis of the proof correctly describing the efficiency of steps is:
B: Using the distributive property first was unnecessary in Step 3 as it was undone in Step 4.
Explanation: In Step 3, the Distributive Property was used to expand the expression (a+b)(a+b) into a(a+b) + b(a+b). However, in Step 4, the like terms ab and ab are combined into 2ab, effectively undoing the Distributive Property. Therefore, using the Distributive Property first in Step 3 was unnecessary and did not contribute to the efficiency of the proof.