中五數學題一問?

👨🏻‍🏫 學術台數學

wai1994926

2011-08-28 7:35 am

determine whether m can be 2 in y=(m-2)x^2+(2m+5)+(m+1) cuts x axis at two points

更新1:

打少了個x,y=(m-2)x^2+(2m+5)x+(m+1)才對,請看清楚題目是問whether m can be 2?

更新2:

但書的笞案寫m cannot be 2

更新3:

我是說自己的問題打少了個x

回答 (1)

胡雪8°

2011-08-31 11:57 pm

✔ 最佳答案

m cannot be 2.

When m = 2, the equation becomes
y = (2 - 2)x² + (2*2 + 5)x + (2 + 1)
i.e. y = 9x + 3

The graph is then a straight line, which cuts the x-axis at 1 point only, but not 2 points.

參考: 胡雪

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