(a) Express f(x) = 5(x^2) - 8x - 2 in the form p(x+q)^2+r, where p, q, and r are constants.
(b) Hence find the minimum value of f(x)
10分 ~~ F.4 quadratic equation
2009-10-03 8:36 am
回答 (1)
2009-10-03 9:48 am
✔ 最佳答案
a)f(x) = 5(x^2) - 8x - 2= 5(x^2 - 8x/5) - 2
= 5[x^2 - 2(4/5)x + (4/5)^2] - 2 - 5(4/5)^2
= 5( x - 4/5)^2 - 26/5
b)when x = 4/5 , the minimum value of f(x) = - 26/5
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