easy 函數

2007-11-13 2:45 am
設 f(x)=3x+2k+1,
如果 f(k)=11,求 k 的值。

如果 f(x)=x 2-kx+k
且 f(-1)=f(2),求 k 的值。

回答 (2)

2007-11-13 2:58 am
✔ 最佳答案
1.f(x) = 3x+2k+1
f(k) = 11
3k+2k+1 = 11
5k+1 = 11
5k = 10
k = 2

2.f(x) = x2﹣kx+k
f(-1) = f(2)
(-1)2﹣k(-1)+k = 22﹣k(2)+k
1+k+k = 4﹣2k+k
2k+1 = 4﹣k
3k = 3
k = 1
2007-11-13 3:15 am
3k+2k+1=11
5k=10
k=2

-1 2-k(-1)+k=2 2-k(2)+k
1+k+k=4-2k+k
k+k+2k-k=4-1
3k=3
k=1


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