question_answer

Find the factors A and B of \[{{x}^{2}}+10x+21\]in the form AB.

A)  (x - 3) (x - 7)        

B)           (x + 3) (x + 7)                    

C)  (x - 3) (x + 7)       

D)            (x + 3) (x,-7)