Question 649571

{{{7x^2-20x=3}}}.....replace {{{-20x}}} with {{{-21x+x}}}

{{{7x^2-21x+x-3=0}}}.......group

{{{(7x^2-21x)+(x-3)=0}}}

{{{7x(x-3)+(x-3)=0}}}

{{{(x-3)(7x+1)=0}}}