1)

(1-√2)(3+√2) = 3 - 3√2 +√2 - (√2)² = 3 - 2√2 - 2 = 1 - 2√2;

2)

(√3+√7)² = (√3)² + 2·√3·√7 +(√7)² = 3+2√21+7 = 10 + 2√21

3)

(2√3 + 1)(1 - 2√3) = (1 + 2√3 )(1 - 2√3) = 1² - (2√3)² = 1 - 4·3 = 1 - 12= - 11

4)

(√2 - √10)² = (√2)² - 2·√2·√10 + (√10)² = 2 - 2√20 + 10 = 12 - 2√4·√5 =

= 12 - 2·2·√5 = 12 - 4√5