2/3(x+8)^2-66=023(x+8)2−66=0
:.2/3(x^2+16x+64)-66=0
:.2/3x^2+32/3x+128/3-66=0
:.2/3x^2+32/3x+128/3-198/3=0
:.2/3x^2+32/3x-70/3=0
multiply both sides by 3
:.2x^2+32x-70=0
:.2(x^2+16x-35)=0
:.x^2+16x-35=0
use quadratic formula
:.x=(-b+-sqrt(b^2-4ac))/(2a)
a=1,b=16,c=-35
:.x=(-16+-sqrt(16^2-4(1)(-35)))/((2)(1))
:.x=(-16+-sqrt(256+140))/2
:.x=(-16+-sqrt(396))/2
x=(-16+-sqrt(11*3*3*2*2))/2
:.x=(-16+-6sqrt(11))/2
:.cancel(-16)^color(magenta)(-8)/cancel2^color(magenta)(1)+-(cancel(-6)^color(magenta)(-3)sqrt(11))/cancel2^color(magenta)(1)
:.-8+-3sqrt11
:.color(magenta)(x=-8+3sqrt11,x=-8-3sqrt11