2條math

Part(c).
pix^3 -pix + 1 = 0
pix^3 = pix - 1
therefore, the line to be added is pix - 1 = y. The intersecting point of this line with the graph of y=pix^3 will be the solutions of the equation.

2008-06-03 22:40:45 補充：
11a. Put x=1, f=1 + 2 -13 +10 = 0, therefore, (x-1) is a factor of f (by Factor Theorem). Therefore, f=(x-1)(x^2 +3x -10) = (x-1)(x-2)(x+5).
11b. Put x=1, f=3 - 7 + 4 = 0, therefore, (x-1) is a factor of f. Therefore, f=(x-1)(3x^2 -4x - 4)
=(x-1)(3x + 2)(x-2).