tolong dong yang bisaa pliss bantuuu

1.
√50 × √20
= √(50 × 20)
= √ 1.000
= 10√10

2.
2√3(2√40 + √12)
= (2√3)(2√40) + (2√3)(√12)
= 4√120 + 2√36
= 4 × 2√30 + 2 × 6
= 8√30 + 12

3.
(√2 + √5)(√2 - √5)
= √4 - √25
= 2 - 5
= -3

4.
(2√5 - 3√3)(2√5 + 3√3)
= 4√25 - 9√9
= 4 × 5 - 9 × 3
= 20 - 27
= -7