Consider polynomial [tex] x^3 - 4x^2 + 7x - 28. [/tex] You can group first two terms and last two terms:
[tex] x^3 - 4x^2 + 7x - 28=(x^3 - 4x^2) + (7x - 28). [/tex]
In first brackets the common factor is [tex] x^2 [/tex] and in second brackets the common factor is 7, then
[tex] x^3 - 4x^2 + 7x - 28=(x^3 - 4x^2) + (7x - 28)=x^2(x-4)+7(x-4)=(x-4)(x^2+7). [/tex]
Answer: the correct answer is D.
