化簡'開方'~[help]!!!急急!!!!急急

2012-09-13 3:36 am

回答 (1)

2012-09-13 10:20 am
✔ 最佳答案
8a.
7√5 + 2√5
= 9√5

8b.
√24 + √54
= √(2²x6) + √(3²x6)
= 2√6 + 3√6
= 5√6

8c.
√80 - √45
= √(4²x5) - √(3²x5)
= 4√5 - 3√5
= √5


=====
9a.
5√5 - 3√2 + 4√2 - 4√5
= (5√5 - 4√5) + (-3√2 + 4√2)
= √5 + √2

9b.
√75 + √50 - √27
= √(5²x3) + √(5²x2) - √(3)³
= 5√3 + 5√2 - 3√3
= 5√2 + (5√3 - 3√3)
= 5√2 + 2√3

9c.
3√32 - 4√64 + 5√16 - 2√8
= 3√(2^5) - 4√(2^6) + 5√(2^4) - 2√(2^3)
= 12√2 - 32 + 20 - 4√2
= (-32 + 20) + (12√2 - 4√2)
= -12 + 8√2


=====
7a.
√6(2√3 + 3√2)
= 2√18 + 3√12
= 2√(3²x2) + 3√(2²x3)
= 6√2 + 6√3

7b.
√8(3√2 - √6)
= 3√16 - √48
= 3√(4²) - √(4²x3)
= 12 - 4√3

7c.
√12(2√6 + 3√8)
= 2√72 + 3√96
= 2√(6²x2) + 3√(4²x6)
= 12√2 + 12√6
參考: micatkie


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