Question 937693
Can you try to factorize the left side?


{{{(7x+- 1)(x+- (-3))}}}, or {{{(7x+- 3)(x+- 1)}}}, four possibilities.  Does one of them work?


(7x+1)(x-3)=....{{{1x-21x}}}...    NO.

(7x-1)(x+3)=......{{{(21-1)x}}}....    NO.


(7x+3)(x-1)...........(7-3)x.......   NO


Last combination will not work either.


You will need to use the formula for the general solution of a quadratic equation.



Follow this formula: 

{{{ax^2+bx+c=0}}};
{{{x=(-b+- sqrt(b^2-4ac))/(2a)}}}