\(3a+2b+2c=0\Rightarrow3a+2b=-2c\)
\(f\left(0\right)=c\) ; \(f\left(\dfrac{3}{2}\right)=\dfrac{9a}{4}+\dfrac{3b}{2}+c=\dfrac{9a+6b+2c}{4}=\dfrac{3\left(3a+2b\right)+2c}{4}=\dfrac{-6c+2c}{4}=-c\)
\(\Rightarrow f\left(0\right).f\left(\dfrac{3}{2}\right)=-c^2\le0\)
\(\Rightarrow f\left(x\right)\) có nghiệm trên đoạn \(\left[0;\dfrac{3}{2}\right]\)



