①2/√2 + √27 - √18②(6√x/4 - 2x√1/x)÷3√x③√20 + √5 / √5 -√1/3 × √12④(3+√6)(3-√6)
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①2/√2 + √27 - √18②(6√x/4 - 2x√1/x)÷3√x③√20 + √5 / √5 -√1/3 × √12④(3+√6)(3-√6)
①2/√2 + √27 - √18
②(6√x/4 - 2x√1/x)÷3√x
③√20 + √5 / √5 -√1/3 × √12
④(3+√6)(3-√6)
①2/√2 + √27 - √18②(6√x/4 - 2x√1/x)÷3√x③√20 + √5 / √5 -√1/3 × √12④(3+√6)(3-√6)
①2/√2 + √27 - √18
=√2+3√3-3√2
=-2√2+3√3
②(6√x/4 - 2x√1/x)÷3√x
=[(6/2)√x-(2x/x)√x]÷3√x
=(3√x-2√x)÷3√x
=√x÷3√x
=1/3
③√20 + √5 / √5 -√1/3 × √12
有没有括号?
=(2√5+√5)/√5-√(1/3×12)
=3√5/√5-√4
=3-2
=1
④(3+√6)(3-√6)
=3²-(√6)²
=9-6
=3
①2/√2 + √27 - √18
=(2√2 )/2 + 3√3 - 3√2
= √2 + 3√3 - 3√2
= 3√3 - 2√2
②(6√x/4 - 2x√1/x)÷3√x
= (6 × (√x)/2 - 2x × (√x)/x) ÷3√x
= (3√x - 2√x)÷3√x
= √x ÷3√x =1/3...
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①2/√2 + √27 - √18
=(2√2 )/2 + 3√3 - 3√2
= √2 + 3√3 - 3√2
= 3√3 - 2√2
②(6√x/4 - 2x√1/x)÷3√x
= (6 × (√x)/2 - 2x × (√x)/x) ÷3√x
= (3√x - 2√x)÷3√x
= √x ÷3√x =1/3
③√20 + √5 / √5 -√1/3 × √12
=(2√5+√5)/√5-√(1/3×12)
=3√5/√5-√4
=3-2
=1
④(3+√6)(3-√6) 用平法差公式(a+b)(a-b)=a^2 -b^2
= 9 - 6
= 3
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