Question 548975
{{{ 7x^2 + 10x = -2 }}}
Divide both sides by {{{7}}}
{{{ x^2 + (10/7)*x = -2/7 }}}
Take 1/2 of the coefficient of {{{x}}},
square it, and add it to both sides
{{{ x^2 + (10/7)*x + (5/7)^2 = -2/7 + (5/7)^2 }}}
{{{ x^2 + (10/7)*x + (5/7)^2 = -14/49 + 25/49 }}}
{{{ x^2 + (10/7)*x + (5/7)^2 = 11/49 }}}
{{{ ( x + (5/7) )^2 = 11/49 }}}
Take the square root of both sides
{{{ x + 5/7 = sqrt(11)/7 }}}
{{{ x = ( -5 +- sqrt(11) ) / 7 }}}
Here's a plot of equation:
{{{ graph( 400, 400, -3, 3, -3, 7, 7x^2 + 10x + 2 ) }}}