Respuesta :

The given trinomial can be factored using the factorization method.

x² + 4x - 21
= x² +7x - 3x - 21
= x(x+7) - 3(x+7)
= (x+7)(x-3)

Thus, (x+7)(x-3) is the factored form of the polynomial.

So the correct answer is option B
jcherry99
Answer B
Comment
This is a good question to learn how to eliminate answers that just cannot be.

A 
Gone. You can't choose A. The middle term is a minus in this choice. (-10x). The question is plus. Also 21 will be plus in the answer when the two factors will be expanded. Not to labor the point, but the question is minus.

C.
Where is the minus anywhere in this choice? Gone as well.

D.
D is the  second best answer. The problem is going to be in the middle term. +3x - 7x = - 4x but the original question is +4x. This is not the right answer, but it is harder to eliminate that the other two.

What's left? The answer is 
B <<<<<<<< answer.

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