Expand your knowledge base with the help of IDNLearn.com's extensive answer archive. Get accurate and detailed answers to your questions from our knowledgeable and dedicated community members.
well, the remainder theorem says that if the polynomial f(x) has a factor of (x-a), then if we just plug in the "a" in f(x) it'll gives a remainder, assuming (x-a) is indeed a factor, then that remainder must be 0, so if f(a) = 0 then indeed (x-a) is a factor of f(x). After all that mumble jumble, let's proceed, we have (x+1), that means [ x - (-1) ], so if we plug in -1 in f(x), we should get 0, or f(-1) = 0, let's see if that's true.
[tex]\begin{array}{llrll} f(-1)&=&2(-1)^3-7(-1)^2-5(-1)+4\\\\ &&2(-1)-7(1)-5(-1)+4\\\\ &&-2-7+5+4\\\\ &&-9+9\\ &&0&~~\checkmark \end{array}[/tex]