1) 5√2 - 4√8 + 3√32 = 5√2 - 4√(4*2) + 3√(16*2) = 5√2 - 4*2√2 + 3*4√2 = 5√2 - 8√2 + 12√2 = (5 - 8 + 12)√2 = 9√2
2) (√75 - √12)√3 = (√(25*3) - √(4*3))√3 = (5√3 - 2√3)√3 = (3√3)√3 = 3 * 3 = 9
3) (√7 – 3)² = (√7)² - 2*3*√7 + 3² = 7 - 6√7 + 9 = 16 - 6√7
4) (√5 + 2√2)(√5 - 2√2) = (√5)² - (2√2)² = 5 - 4*2 = 5 - 8 = -3