equation of lines
2011-08-16 5:14 am
回答 (1)
2011-08-16 6:09 am
✔ 最佳答案
x^2 + 3xy + 2y^2 + 3x + 5y + 2= (x + y)(x + 2y) + 3x + 5y + 2
= (x + y + a)(x + 2y + b)
where :
ab = 2 ............(1)
a + b = 3 (coefficient of x)......(2)
2a + b = 5 (coefficient of y) ...........(3)
so a = 2 and b = 1 satisfies all 3 equations.
so the lines are x + y + 2 = 0 and x + 2y + 1 = 0.
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原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110815000051KK01324