To solve the quadratic equation \(84x^2 + 16x = 0\) by factoring out the greatest common factor (GCF), we first identify the GCF of the two terms:
The GCF of \(84x^2\) and \(16x\) is \(4x\).
Now, we can factor \(4x\) out of the equation:
\[ 84x^2 + 16x = 4x(21x + 4) = 0 \]
Now we set each factor equal to zero:
-
\(4x = 0\)
This gives us:
\[ x = 0 \] -
\(21x + 4 = 0\)
Solving for \(x\):
\[ 21x = -4
\] \[ x = -\frac{4}{21} \]
So the solutions to the equation \(84x^2 + 16x = 0\) are: \[ x = 0 \quad \text{and} \quad x = -\frac{4}{21} \]
Thus, the correct option is:
The solutions are \(x = -\frac{4}{21}\) and \(x = 0\).