Evaluate the following: (The answers can be expressed in surd form) (question 1-2)
x=mutiply
√=開方符號
1a) 3√(27) x 2√(12) x √(5)
b) 4^√( 6) -√(6)^3
2a) [3√(5)-√(3)][2√(3)+4√(5)]
b) [√(5)-√(2)] [√(5)+√(2)]
3. If √(2) = 1.414. withous using a calculator, find the value of √(32)^8
(correct to the 3 significant figures)
Maths 問題!!!!請教導! 謝謝! Help me!
2010-08-05 7:39 am
回答 (2)
2010-08-05 6:21 pm
✔ 最佳答案
1a)3√(27) x 2√(12) x √(5)
= 3√(3³) x 2√(2² x 3) x √(5)
= 3 x 3√(3) x 2 x 2√(3) x √(5)
= 36 x [√(3)]² x √(5)
= 36 x 3 x √(5)
= 108√(5)
1b)
4√(6) - √(6)³
= 4√(6) - 6√(6)
= -2√(6)
2a)
[3√(5) - √(3)][2√(3) + 4√(5)]
= 3√(5)[2√3 + 4√5) - √3[2√(3) + 4√(5)]
= 6√15 + 60 - 6 - 4√(15)
= 54 + 2√(15)
2b)
[√(5) - √(2)][√(5) + √(2)]
= [√(5)]² - [√(2)]²
= 5 - 2
= 3
3.
√(32)⁸
= (32)⁴
= (1024)²
= 1048576
= 1050000 (3 sig. fig.)
2010-08-06 00:08:43 補充：
4.
√(32)/8
= √(4² x 2)/8
=4√(2)/8
= √(2)/2
= 1.414/2
= 0.707 (to 3 sig. fig.)
參考: adam, adam
2010-08-05 7:46 pm
收錄日期: 2021-04-16 11:34:39
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100804000051KK02281