Question 199786
when  there  are  four  terms,  try  factoring  by  grouping
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2x^3 -14x +3x -21
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2x (x-7) +3(x-7},,,,,,like ab +cb= (a+c)b ,,,but  b=(x-7)
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(2x+3) (x-7)
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check  by  subst  x=1  in  original  and  answer,  ok