为了简便书写,分别将三组x, y的值写成:
x1, y1; x2, y2; x3,y3
因为y=ax^b + c, 则有:
y1=ax1^b + c--------------------(1)
y2=ax2^b + c--------------------(2)
y3=ax3^b + c--------------------(3)
有:
y1 - y2 =a(x1^b - x2^b); --------(4)
y2 - y3 =a(x2^b - x3^b) ----------(5)
∴ (y1-y2)/(y2-y3)=(x1^b - x2^b)/(x2^b - x3^b) ----> 将x, y的值带入则可以求得b的值;然后将b带入(4)或(5)可以求得a;再由(1)或(2)或(3)求的c
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