functions and graphs_0
2017/06/21 02:37
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標題:
functions and graphs
it is given that f(x)=x^2-kx (a) find f(x+2) and f(x-2) in term of k. (b) if f(x+2) - f(x-2) = kx-32. find the value of k (c) hence, solve for x if f(x+2) = f(x-2) +40
最佳解答:
f(x) = x2 - kx (a) f(x+2) = (x+2)2 - k(x+2) = x2 + 4x + 4 - kx -2k = x2 - (k-4)x + 4 -2k f(x-2) = (x-2)2 - k(x-2) = x2 - 4x + 4 - kx +2k = x2 - (k+4)x + 4 +2k (b) f(x+2) - f(x-2) ≡ kx - 32 8x - 4k ≡ kx - 32 k = 8 (c) f(x+2) = f(x-2) +40 f(x+2) - f(x-2) = 40 kx - 32 = 40 8x - 32 = 40 x - 4 = 5 x = 9
其他解答:
(a) f(x)=x^2-kx f(x+2)=(x+2)^2-(x+2)k f(x+2)=x^2+4x+4-kx-2k f(x+2)=x^2+4x-kx+4-2k f(x-2)=(x-2)^2-k(x-2) f(x-2)=x^2-4x+4-kx+2k f(x-2)=x^2-4x-kx+4+2k (b) f(x+2) - f(x-2) = kx-32 x^2+4x-kx+4-2k-x^2+4x+kx-4-2k=kx-32 8x-4k=kx-32 k=8 (c) f(x+2) = f(x-2) +40 x^2-4x-8-x^2+12x-20=40 8x=68 x=8.5
functions and graphs
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發問:it is given that f(x)=x^2-kx (a) find f(x+2) and f(x-2) in term of k. (b) if f(x+2) - f(x-2) = kx-32. find the value of k (c) hence, solve for x if f(x+2) = f(x-2) +40
最佳解答:
f(x) = x2 - kx (a) f(x+2) = (x+2)2 - k(x+2) = x2 + 4x + 4 - kx -2k = x2 - (k-4)x + 4 -2k f(x-2) = (x-2)2 - k(x-2) = x2 - 4x + 4 - kx +2k = x2 - (k+4)x + 4 +2k (b) f(x+2) - f(x-2) ≡ kx - 32 8x - 4k ≡ kx - 32 k = 8 (c) f(x+2) = f(x-2) +40 f(x+2) - f(x-2) = 40 kx - 32 = 40 8x - 32 = 40 x - 4 = 5 x = 9
其他解答:
(a) f(x)=x^2-kx f(x+2)=(x+2)^2-(x+2)k f(x+2)=x^2+4x+4-kx-2k f(x+2)=x^2+4x-kx+4-2k f(x-2)=(x-2)^2-k(x-2) f(x-2)=x^2-4x+4-kx+2k f(x-2)=x^2-4x-kx+4+2k (b) f(x+2) - f(x-2) = kx-32 x^2+4x-kx+4-2k-x^2+4x+kx-4-2k=kx-32 8x-4k=kx-32 k=8 (c) f(x+2) = f(x-2) +40 x^2-4x-8-x^2+12x-20=40 8x=68 x=8.5
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