Question

1 пример(3V3 + 2V7+V21+6)(3V3+2V7-V21-6) 
2 пример(4V5-4-V55+V11)(4V5+4+V55+V11)
где V-корень
3 пример(4V7-V119-4V3+V51)(4V7+V119+4V3+V51)
(5V3+2V30-2V20-5V2)(5V3-2V30-V2V20+5V2)
V2V20+5V2 в 4 примере все под корнем

Answer 1

$(3 sqrt{3} + 2 sqrt{7}+ sqrt{21} +6)(3sqrt{3} +2 sqrt{7}-sqrt{21} -6) = \ =(3sqrt{3} +2 sqrt{7})^2-(sqrt{21} +6)^2= \ =27+28+12 sqrt{21} -21-36-12 sqrt{21} =-2$

$(4 sqrt{5}+ sqrt{11}-4- sqrt{55}})(4 sqrt{5}+ sqrt{11}+4+ sqrt{55})= \ =(4sqrt{5}+ sqrt{11})^2-(4+ sqrt{55})^2= 80+11+8 sqrt{55} -16-55-8 sqrt{55}= \ =20$

$(4 sqrt{7}-sqrt{119}-4sqrt{3}+sqrt{51})(4sqrt{7}+sqrt{51}+sqrt{119}+4sqrt{3})= \ (4sqrt{7}+sqrt{51})^2-(sqrt{119}+4sqrt{3})^2= \ =112+51+8 sqrt{357} -119-48-8sqrt{357} =-4$