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Đáp án:

 `->a)P=- (sqrt(6))/2`$\\$`->b)Q=2`

Giải thích các bước giải:

 `P = (2sqrt(8) - sqrt(12))/(sqrt(18) - sqrt(48)) - (sqrt(5) + sqrt(27))/(sqrt(30) + sqrt(162))`$\\$`=(4sqrt(2) - 2sqrt(3))/(3sqrt(2) - 4sqrt(3)) - (sqrt(5) + 3sqrt(3))/(sqrt(30) + 9sqrt(2))`$\\$`=((4sqrt(2) - 2sqrt(3))(3sqrt(2) + 4sqrt(3)))/- 30 - ((sqrt(5) + 3sqrt(3))(sqrt(30) - 9sqrt(2)))/- 132`$\\$`=- ((4sqrt(2) - 2sqrt(3))(3sqrt(2) + 4sqrt(3)))/30 - (sqrt(150) - 9sqrt(10) + 3sqrt(90) - 27sqrt(6))/- 132`$\\$`=- (2(2sqrt(2) - sqrt(3))(3sqrt(2) + 4sqrt(3)))/30 - (sqrt(150) - 9sqrt(10) + 9sqrt(10) - 27sqrt(6))/- 132`$\\$`=- ((2sqrt(2) - sqrt(3))(3sqrt(2) + 4sqrt(3)))/15 - (5sqrt(6) - 27sqrt(6))/- 132`$\\$`=- (12 + 8sqrt(6) - 3sqrt(6) - 12)/15 - (- 22sqrt(6))/- 132`$\\$`=- (5sqrt(6))/15 - (sqrt(6))/6`$\\$`=- (sqrt(6))/2`$\\$`b)Q = (3 + 2sqrt(3))/(sqrt(3)) + (2 + sqrt(2))/(sqrt(2) + 1) - (sqrt(2) + sqrt(3))`$\\$`=((3 + 2sqrt(3)) * sqrt(3))/3 + (2 + sqrt(2))(sqrt(2) - 1) - sqrt(2) - sqrt(3)`$\\$`=(3sqrt(3) + 6)/3 + 2sqrt(2) - 2 + 2 - sqrt(2) - sqrt(2) - sqrt(3)`$\\$`=(3sqrt(3) + 6)/3 + 0 - sqrt(3)`$\\$`=(3(sqrt(3) + 2))/3 - sqrt(3)`$\\$`=sqrt(3) + 2 - sqrt(3)`$\\$`=2`