Find the valies of a and b such that in the expansion of (x+a)(x+b),the coeffcient of the x term is a positive number and the constand term is a negative number.
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MATH f.1升f.2
2008-08-21 11:35 pm
回答 (1)
2008-08-22 1:12 am
✔ 最佳答案
First, express (x+a)(x+b) : x^2 + (a+b)x + abthe coeffcient of the x term is a positive number
即是說 (a+b) 要係正數
the constand term is a negative number.
即是說 ab 要係負數
成條問題就係要你諗a,b兩個數係咩先可以令上面兩個情況成立
ab 要係負數 --> 即係其中一個要係負( 因為負正得負)
事旦當a係-5, 咁(a+b) 要係正數, 即係 b-5要係正數
所以b 係6, 係100, 係1000都可以
參考: Me
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