A.1
B.a
C.-2a
D.1-2a
更新1:
it should be x^2-2a^2 not x^2+2a^2 in the first part !!!!! +.+
maths explain please !!
回答 (1)
2012-08-06 5:46 am
✔ 最佳答案
x^2+2a^2-b^2=2(x+a)^2-(x-b)^2x^2+2a^2-b^2=2(x^2+2ax+a^2)-(x^2-2bx+b^2)
x^2+2a^2-b^2=2x^2+4ax+2a^2-x^2+2bx-b^2
x^2+2a^2-b^2=x^2+4ax+2a^2+2bx-b^2
So, 4a + 2b = 0 => b = -2a (C)
收錄日期: 2021-04-22 00:59:29
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20120805000051KK00471