I think you're asking what is the difference between the remainder theorem and the factor theorem? The Remainder Theorem: When we divide a polynomial f(x) by x-c the remainder equals f(c) The Factor Theorem: When f(c)=0 then x-c is a factor of the polynomial When x-c is a factor of the polynomial then f(c)=0 ----------------------------- 1. Use the remainder theorem to find what you get when you substitute -3 for x in f(x) = 3x^3 - 5x^2 + 7x - 4, whch is f(-3). Then check your answer by actually substituting -3 in f(x) to find f(-3) -3 | 3 -5 7 -4 | -9 42 -147 3 -14 49 -151 So f(-3) = -151, the number in the lower right corner of the synthetic division. Checking by actually substituting -3 for x in f(x) f(x) = 3x^3 - 5x^2 + 7x - 4 f(-3) = 3(-3)^3 - 5(-3)^2 + 7(-3) - 4 f(-3) = 3(-27) - 5(9) -21 - 4 f(-3) = -81 - 45 - 21 - 4 f(-3) = -151 2. Use the factor theorem to show that x-2 is a factor of x^4-7x^2+x+10 2 | 1 0 -7 1 10 | 2 4 -6 -10 1 2 -3 -5 0 Edwin