it is given that f (x) = (x+3)(x+2)-k^2 and f (k)=2k
A..find the value of k
B..hence, solve for x if 2x- f (x)=0
f.4 maths
2007-10-22 8:27 am
回答 (2)
2007-10-22 8:51 am
✔ 最佳答案
A. f(k) = 2k(k+3)(k+2) - k^2 = 2k
k^2 + 5k+6 - k^2 = 2k
3k+6 = 0
k = -6/3 = -2
B. 2x-f(x) = 0
2x - (x+3)(x+2) + (-2)^2 = 0
2x - x^2 - 5x - 6 + 4 = 0
x^2 + 3x + 2 = 0
(x+1)(x+2) = 0
x = -1 or -2
There should be two answer in part B: x = -1 or x = -2
2007-10-22 8:36 am
A. f(k) = (k+3)(k+2) - k^2 = 2k
k^2 + 5k + 6 - k^2 = 2k
3k + 6 = 0
k = -2
B. 2x - f(x) = 0
f(x) = 2x
x = -2 (By (A))
k^2 + 5k + 6 - k^2 = 2k
3k + 6 = 0
k = -2
B. 2x - f(x) = 0
f(x) = 2x
x = -2 (By (A))
收錄日期: 2021-04-13 18:12:42
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