SAT Math Question of the Day

Math Category: Roots Level 2:

Q: √ 4 + √ 8

  1. 2 √ 2
  2. 4 √ 2
  3. 2 + 2 √ 2
  4. √ 12
  5. 5 + √ 2

UNANSWERED.

The correct answer is C.

A: The answer is 2 + 2 √ 2 .

√ 4 = √ (2)(2) = 2
√ 8 = √ (2)(2)(2)
There are two 2's, so the 2 can be moved to outside the root, leaving 2 √ 2 .

Note: you can't add the roots together.
√ 4 + √ 8 does not equal √ 4 + 8 .

√ (4 + 8) = √ 12 = √ (2)(2)(3) = 2 √ 3 .