1,解方程(開方7-2)x=6.
2,化簡(開方2-i)^2(開方2+i)^3,答案以標準式表示.
3,已知a=開方3-4i及b=開方3+4i.求a^2+ab+b^2的值.
數系的發展
2009-09-15 5:09 am
回答 (1)
2009-09-15 7:10 am
✔ 最佳答案
1)(√7 - 2)x = 6
x = 6 / (√7 - 2)
x = 6(√7 + 2) / [(√7 - 2)(√7 + 2)]
x =( 6√7 + 12) / (7-4)
x = 2√7 + 4
2)(√2 - i)^2 * (√2 + i)^3
= (√2 + i)[(√2 - i)(√2 + i)]^2
= (√2 + i) (2+1)^2
= 9√2 + 9i
3) a^2+ab+b^2
= (a+b)^2 - ab
= [(3-4i)+(3+4i)]^2 - (3-4i)(3+4i)
= 6^2 - (9+16)
= 36 - 25
= 11
收錄日期: 2021-04-21 22:05:54
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