A= 2√18+√32-√50
= 2√3²x2 + √2²x2²x2 - √5²x2
= 2x3√2 + 2x2√2 -5√2
= 6√2 + 4√2 -5√2
= 5√2
B= 3√5 -2√20 +3√80
= 3√5 -2√2²x5 + 3√2²x2²x5
= 3√5 - 2x2√5 + 3x2x2√5
= 3√5 - 4√5 + 12√5
= 11√5
C= 2√24 -√96 -√600
= 2√2²x6 - √3x2²x2²x2 -√10²x6
= 2x2√6 - 2x2√6 -10√6
= 4√6 -4√6 -10√6 ( tu simplifies )
= -10√6