SAT Math Question of the Day

Math Category: Roots Level 2:

Q: 2 √ 2  + 4 √ 5  + 7 √ 2  + 2 √ 5

  1. 2 √ 2  + √ 3
  2. 4 √ 2  + 3 √ 3
  3. 5 √ 2  + 4 √ 3
  4. √ 5  + 2 √ 6
  5. 9 √ 2  + 6 √ 5

UNANSWERED.

The correct answer is E.

A: The answer is 9 √ 2  + 6 √ 5 .

Add like terms: 2 √ 2  + 7 √ 2 is 9 √ 2.
4 √ 5 + 2 √ 5 is 6 √ 5.
Another way to imagine it is to replace √ 2 with an Apple and √ 5 with a Banana.   2 Apples + 7 Apples = 9 Apples, so that's 9 √ 2 .   4 Bananas + 2 Bananas = 6 Bananas, so that's 6 √ 5 .