SAT Math Question of the Day

Math Category: Roots Level 2:

Q: √ 4 + √ 5

  1. 3
  2. 2 √ 5
  3. 2 + √ 5
  4. 2 √ 10
  5. 5 + √ 4

UNANSWERED.

The correct answer is C.

A: The answer is 2 + √ 5 .

√ 4 = √ (2)(2)
There are two 2's, so the 2 can be moved to outside the root, leaving 2.
√ 5 can't be simplified further.

Note: you can't add the roots together, as in
√ (4 + 5) = √ 9 = √ (3)(3) = 3.
√ 4 + √ 5 does not equal √ 9 .