Question 810403
{{{7x^2+2x-1=0}}}

{{{7(x^2+(2/7)x-1/7)=0}}}

{{{7(x^2+(2/7)x+(2/(2*7))^2-1/7)=0+7(2/(2*7))^2}}}

{{{7(x^2+(2/7)x+(1/7)^2-1/7)=7(1/7)^2}}}

{{{7((x+1/7)^2-1/7)=1/7}}}

{{{7(x+1/7)^2-1=1/7}}}

{{{(x+1/7)^2=(1/7)(1+1/7)}}}

{{{(x+1/7)^2=8/49}}}

{{{x=-1/7+- sqrt(8/49)}}}

{{{highlight(x=-1/7+- (2/7)sqrt(2))}}}