Respuesta :

The answer is :A. x=3 or x=-7
apologiabiology
minus 25 oth sides
x^2+4x-21
facotr
what 2 numbes multiply to -21 and add to 4?
-3 and 7
(x-3)(x+7)=0

set to zero
x-3=0
x=3

x+7=0
x=-7


x=3 or -7

A is answer

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