Răspuns:
Explicație pas cu pas:
6)
a = √5 × ( 4√2 - 3√5 ) - 2 ( 2√10 + 3 )
a = 4√10 - 3√25 - 4√10 - 6
a = - 3 × 5 - 6
a = - 15 - 6
a = - 21 ∈ Z
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b = 2√7 × ( 3 - √3 ) + 2 × ( 4 + √21) - 6√7
b = 6√7 - 2√21 + 8 + 2√21 - 6√7
b = ( 6√7 - 6√7 ) + ( - 2√21 + 2√21 ) + 8
b = 0 + 0 + 8
b = 8 ∈ Z
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c = √12 × ( √32 - 3√3 ) - 4 × ( 7 + 2√6 )
√12 = √(4×3) = 2√3
√32 = √(16×2) = 4√2
c = 2√3 × 4√2 - 2√3 × 3√3 - 28 - 8√6
c = 8√6 - 6×3 - 28 - 8√6
c = - 18 - 28
c = - 46 ∈ Z
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d = √48 × ( √8 - √3) - 2√2 × ( 4√3 - √2)
√48 = √(16×3) = 4√3
√8 = √(2²×2) = 2√2
d = 4√3 × 2√2 - 4√3 × √3 - 8√6 + 2√4
d = 8√6 - 4 × 3 - 8√6 + 2 × 2
d = - 12 + 4
d = - 8 ∈ Z
