F.4 Maths

👨🏻‍🏫 學術台數學

[匿名]

2014-10-07 9:09 pm

Consider the function f(x)=ax^2+ bx+c. If f(0)=3, f(2)=13,and f(4)=55, find the value of a, b, and c.
I found:
a+b+c =3
4a+2b+c =13
16a+4b+c =55
I do not know how to do next step?

更新1:

Would you mind to show me what is the best way to do this question? Thanks

更新2:

Would you mind to show me what is the best way to do this question? Thanks

回答 (3)

YA HOO！知識＋管理員

2014-10-07 11:11 pm

✔ 最佳答案

其實你個問題只係substitute哥到出錯
如果你 f(0)=3 無substitute錯, 就應該可以搵到 a=? b=? c=?

圖片參考：https://s.yimg.com/rk/HA07344914/o/1808798841.png

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螞蟻雄兵

2014-10-08 1:06 am

Consider the function f(x)=ax^2+bx+c，If f(0)=3，f(2)=13，and f(4)=55，find
the value of a，b，and c
Sol
f(x)=a(x－0)(x－2)+p(x－0)+3
f(2)=2p+3=13
p=5
f(x)=a(x－0)(x－2)+5x+3
f(4)=a*4*2+23=55
a=4
f(x)=4(x^2－2x)+5x+3=4x^2－3x+3
a=4，b=－3，c=3

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用戶10012

2014-10-07 10:32 pm

a + b + c = 3 is wrong. It should be c = 0 for x = 0.

2014-10-07 14:33:29 補充：
Sorry, it should be c = 3 for x = 0.

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