Respuesta :
x^2-(7-3)x-21=0
=>x^2-7x+3x-21=0
=>x(x-7)+3(x-7)=0
=>(x+3)(x-7)=0
therefore, (x-7)(x+3) is the correct answer.
=>x^2-7x+3x-21=0
=>x(x-7)+3(x-7)=0
=>(x+3)(x-7)=0
therefore, (x-7)(x+3) is the correct answer.