A = √50 + 4√18 − 7√8
= √(25 × 2) + 4√(9 × 2) − 7√(4 × 2)
= 5√2 + 4 × 3√2 − 7 × 2√2
= (5 + 12 − 14)√2
= 3√2
B = √20 − 8√45 + 2√5
= √(4 × 5) − 8√(9 × 5) + 2√5
= 2√5 − 8 × 3√5 + 2√5
= (2 − 24 + 2) √5
= −20√5
C = √12 + √75 + 4√300
= √(4 × 3) + √(25 × 3) + 4√(100 × 3)
= 2√3 + 5√3 + 4 × 10√3
= (2 + 5 + 40)√3
= 47√3
D = 5√63 − √28 + √7
= 5√(9 × 7) − √(4 × 7) + √7
= 5 × 3√7 − 2√7 + √7
= (15 − 2 + 1)√7
= 14√7
