(超急~唔該!)數3題~~~~~10分10分

1.
√80 - 2√20
= √(4^2 x 5) - 2√(2^2 x 5)
= 4√5 - 4√5
= 0


2.
√24 - √54 + √96
= √(2^2 x 6) - √(3^2 x 6) + √(4^2 x 6)
= 2√6 - 3√6 + 4√6
= (2 - 3 + 4)√6
= 3√6


3.
√108 + 2√128 - √147
= √(6^2 x 3) + 2√(8^2 x 2) - √(7^2 x 3)
= 6√3 + 16√2 - 7√3
= 16√2 - √3

1)√80 - 2√20
=√2*2*2*2*5 - 2√2*2*5
=2^2√5 - 2*2√5
=4√5 - 4√5
=0


2)√24- √54 +√96
=√2*2*2*3 - √2*3*3*3 + √2*2*2*2*2*3
=2√2*3 - 3√2*3 + 2^2√2*3
=2√6 - 3√6 + 4√6
=3√6


3)√108 + 2√128 - √147
=√2*2*3*3*3 + 2√2*2*2*2*2*2*2 - √3*7*7
=2*3√3 + 2*2*2*2√2 - 7√3
=6√3 + 16√2 - 7√3
=16√2-√3


I hope I can help you.

1.√80 - 2√20
= √(4×20) - 2√20
= √4 × √20 - 2√20
= 2√20 - 2√20
= 0

2.√24 - √54 + √96
= √(4×6) - √(9×6) + √(16×6)
= √4 × √6 - √9 × √6 + √16 × √6
= 2√6 - 3√6 + 4√6
= 3√6

3.√108 + 2√128 - √147
= √(36×3) + 2√(2^7) - √(49×3) ......... ^ = 次方
= √36 × √3 + 2√(2^6)(2) - √49 × √3
= 6√3 + 2√2^6 × √2 - 7√3
= 6√3 + 2(2^3) × √2 - 7√3
= 6√3 + (2^4)√2 - 7√3
= 16√2 - √3