1. √8 – √20 + 3√45=

1 √8 – √20 + 3√45
= √4 × √2 – √4 × √5 + 3 √9 × √5
= 2√2 – 2√5 + 3 × 3√5
= 2√2 – 2√5 + 9√5
= 2√2 + 7√5
2 √42 – 2√13 + √1024 – 3√45
= √42 – 2√13 + 32 – 3√9 × √5
= √42 – 2√13 + 32 – 3 × 3√5
= √42 – 2√13 + 32 – 9√5
3 6√72 – 6√8 + √20 – 3√45
= 6√9 × √8 – 6√4 × √2 + √4 × √5 – 3√9 × √5
= 6 × 3√8 – 6 × 2√2 + 2√5 – 3 × 3√5
= 18√8 – 12√2 + 2√5 – 9√5
4 √48 – √75 + √363
= √16 × √3 – √25 × √3 + √121 × √3
= 4√3 – 5√3 + 11√3
= -1√3 + 11√3
= 10√3