Question 178400
{{{-x^2 + 7x - 10 = 0}}}
When the equation is in the form
{{{ax^2 + bx + c = 0}}}, you can use the 
quadratic formula which is:
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
{{{a = -1}}}
{{{b = 7}}}
{{{c = -10}}}
{{{x = (-7 +- sqrt( 7^2-4*(-1)*(-10) ))/(2*(-1)) }}}
{{{x = (-7 +- sqrt( 49 - 40 ))/(-2) }}}
{{{x = (-7 +- sqrt( 9 ))/(-2) }}}
The 2 answers are:
{{{x = (7 - 3) / 2}}}
{{{x = 2}}}
and
{{{x = (7 + 3) / 2}}}
{{{x = 5}}}
I can see directly that this is true, since
{{{-x^2 + 7x - 10 = (-x + 5)(x - 2)}}}
and
{{{(-x + 5)(x - 2) = 0}}}
{{{(-5 + 5)(5 - 2) = 0}}}
{{{0*3 = 0}}}
{{{0 = 0}}}
{{{(-2 + 5)(2 - 2) = 0}}}
{{{3*0 = 0}}}
{{{0 = 0}}}