Answer:
D. 9 + 4√5
Step-by-step explanation:
What we're essentially doing here is squaring 2 + √5. (2 + √5 and 2 + 1√5 are essentially the same)
(2 + √5)(2 + √5) (I didn't put the one on the conjugate for a reason; look above)
Step 1: Apply the distributive property by multiplying each term of 2 + √5 by 2 + √5
4 + 2√5 + 2√5 + (√5)²
Step 2: Combine 2√5 and 2√5 to get 4√5.
4 + 4√5 + (√5)²
Step 3: The square of √5 is 5.
4 + 4√5 + 5
Step 4: Add 4 and 5 to get 9.
9 + 4√5 is the final answer to this question.
