Question

tìm nghiệm 
b(x)=\(^{\left(-2x\right)^2}\) - 3x + 21 -\(4x^2\)

Answer 1

\(B\left(x\right)=0\)

\(\Rightarrow\left(-2x\right)^2-3x+21-4x^2=0\)

\(\Rightarrow4x^2-3x+21-4x^2=0\)

\(\Rightarrow-3x+21=0\)

\(\Rightarrow-3x=-21\)

\(\Rightarrow x=\dfrac{21}{3}\)

\(\Rightarrow x=7\)