대답:
# sqrt125 + sqrt (1/5) -sqrt (49/5) = 19 / sqrt5 #
설명:
# sqrt125 = sqrt (25 * 5) = sqrt (25 * 25 / 5) = sqrt (25 ^ 2 / 5) = sqrt (25 ^ 2) / sqrt5 = 25 / sqrt5 #
#sqrt (1/5) = sqrt1 / sqrt5 = 1 / sqrt5 #
#sqrt (49/5) = sqrt (7 ^ 2 / 5) = sqrt (7 ^ 2) / sqrt5 = 7 / sqrt5 #
#rarr sqrt125 + sqrt (1/5) -sqrt (49/5) = 25 / sqrt5 + 1 / sqrt5-7 / sqrt5 = (25 + 1-7) / sqrt5 = 19 / sqrt5 #
