y=x2次-x-6的圖像與x軸交於A(a,0)和B(b,0),與y軸交於C(0,c),如圖所示. 求a,b同c.
要請楚列明部就
一條好難的數學題 識就入黎
2006-10-30 10:45 pm
回答 (2)
2006-10-30 10:54 pm
✔ 最佳答案
y=x^2-x-6c = y-intercept(y交點) = -6
Put A(a,0) into y=x^2-x-6
0=a^2-a-6
0=(a-3)(a+2)
a=3 or -2
Put B(b,0) into y=x^2-x-6
0=b^2-b-6
0=(b-3)(b+2)
b=3 or -2
跟著要睇番幅圖先知a 同 b 係正數定負數...
如果a=3, b就= -2 掉番轉一樣~~
c就一定係 -6
參考: me
2006-10-30 10:54 pm
y = x^2 -x -6
since, y- intercept(中文是截距嗎？）= c
so 代 x=0,
y = -6
c= -6
解 y = x^2-x-6 = 0
(x+2)(x-3) =0
x = -2 或 x =3
so a = -2, b= 3 或
a = 3, b= -2
since, y- intercept(中文是截距嗎？）= c
so 代 x=0,
y = -6
c= -6
解 y = x^2-x-6 = 0
(x+2)(x-3) =0
x = -2 或 x =3
so a = -2, b= 3 或
a = 3, b= -2
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