Factor completely. show all steps please
Solve x^2 - 3x -21 = 0
Solve x^2 - 3x -21 = 0
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x^2 - 3x -21 = 0
(x-3/2)^2-9/4-21=0
(x-3/2)^2-93/4=0
(x-3/2)^2-[sqrt(93)/2]^2=0
(x-3/2-sqrt(93)/2)(x-3/2+sqrt(93)/2)=0
(x-{3+sqrt(93)}/2)(x-{3-sqrt(93)}/2)=0
(x-3/2)^2-9/4-21=0
(x-3/2)^2-93/4=0
(x-3/2)^2-[sqrt(93)/2]^2=0
(x-3/2-sqrt(93)/2)(x-3/2+sqrt(93)/2)=0
(x-{3+sqrt(93)}/2)(x-{3-sqrt(93)}/2)=0
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you can't answer this because no factors of 21 add or subtract to get -3.