#5(x+3)^2+116=361#
#:.5(x+3)^2=245#
#:.(x+3)^2=49#
#:.x+3=sqrt49#
#:.x=-3+-sqrt49#
#:.color(blue)(x=-3+7=4#
#:.color(blue)(or x=-3-7=-10#
substitute #color(blue)(x=4#
#:.5(color(blue)(4))+3)^2+116=361#
#:.5(7^2)+116=361#
#:.5(49)+116=361#
#:.245+116=361#
#color(blue)(361=361#
substitute #color(blue)(x=-10#
#:.5(color(blue)((-10))+3)^2+116=361#
#:.5(-7)^2+116=361#
#:.5(49)+116=361#
#:.245+116=361#
#color(blue)(361=361#