Answer
$15 + 4 \sqrt 14$
Work Step by Step
$( \sqrt 7 + \sqrt 8 ) ( \sqrt 7 + \sqrt 8 )$
Use FOIL to simplify. FOIL: First (Multiply the first variables in the brackets), outside (Multiply the outer variables), Inside (Multiply the inside variables), Last (Multiply the last variables in the brackets).
$7 + \sqrt 7 \sqrt 8 + \sqrt 7 \sqrt 8 + 8$
We add the radicals together and the numbers together
$15 + 2 \sqrt 7 \sqrt 8$
We multiply 7 and 8 and bring them under the same radical
$15 + 2 \sqrt 7 \times 8$
$15 + 2 \sqrt 4 \times 14$
Square root of 4 is 2 because 2 x 2 = 4
$15 + 4 \sqrt 14$
