The quadratic formula states:
For #color(red)(a)x^2 + color(blue)(b)x + color(green)(c) = 0#, the values of #x# which are the solutions to the equation are given by:
#x = (-color(blue)(b) +- sqrt(color(blue)(b)^2 - (4color(red)(a)color(green)(c))))/(2 * color(red)(a))#
Substituting:
#color(red)(6)# for #color(red)(a)#
#color(blue)(-7)# for #color(blue)(b)#
#color(green)(-3)# for #color(green)(c)# gives:
#x = (-color(blue)(-7) +- sqrt(color(blue)(-7)^2 - (4 * color(red)(6) * color(green)(-3))))/(2 * color(red)(6))#
#x = (7 +- sqrt(49 - (-72)))/12#
#x = (7 +- sqrt(49 + 72))/12#
#x = (7 +- sqrt(121))/12#
#x = (7 +- 11)/12#
#x = (7 - 11)/12#; #x = (7 + 11)/12#
#x = (-4)/12#; #x = 18/12#
#x = -1/3#; #x = 3/2#