Answer :
Answer:
x= -1/3
x = -7
Step-by-step explanation:
9x^2 +66x+21 = 0
a=9 b=66 c=21
quadratic formula
x=(-b +/- square root of (b^2 – 4ac))/(2a)
x = (-66 +/- square root of (66^2 -4*9*21))/(2*9)
x = (-66 +/- square root of (4356 -756))/(18)
x = (-66 +/- square root of (3600))/(18)
x = (-66 +/- 60)/18
split the fraction
(-66 +/- 60)/18 = -6/18 and -126/18 because of the +/-
x = -6/18 x = -126/18
x = -1/3 x = -7
[tex]~~~~~~9x^2+66x+21 = 0\\\\\implies 3(3x^2+22x+7)=0\\\\\implies 3x^2+22x+7=0\\\\\implies 3x^2 +21x +x +7=0\\\\\implies 3x(x+7) +(x+7)=0\\\\\implies (x+7)(3x+1)=0\\\\\implies x = -7~~ \text{or}~~ x =-\dfrac 13[/tex]