Quadratic Equation
First combine like terms and rewrite the equation in standard form.
#7x^2-5=2x+9x^2#
Move all terms to the left side.
#7x^2-5-2x-9x^2=0#
Simplify.
#-2x^2-5-2x-9x^2=0#
Rewrite in standard form: #ax^2+bx+c=0#.
#-2x^2-2x-5=0#,
where #a=-2#, #b=-2#, and #c=-5#.
Quadratic Formula
#x=(-b+-sqrt(b^2-4ac))/(2a)#
Plug in the known values.
#x=(-(-2)+-sqrt((-2)^2-4*-2*-5))/(2*-2)#
Simplify.
#x=(2+-sqrt(-36))/(-4)#
Simplify.
#x=-(2+-6i)/(4)#
#x=-(2+6i)/(4),# #(-2-36i)/(4)#
Reduce.
#x=-(color(red)cancel(color(black)(2^1))+color(red)cancel(color(black)(6^(3)))i)/color(red)cancel(color(black)(4^2)),# #-(color(red)cancel(color(black)(2^1))-color(red)cancel(color(black)(6^(3)))i)/color(red)cancel(color(black)(4^2)),#
#x=-(1+3i)/2,# #x=-(1-3i)/2#
