To solve the quadratic equation \(84x^2 + 16x = 0\) by factoring out the greatest common factor (GCF), we first identify the GCF of the terms in the equation.
The GCF of \(84x^2\) and \(16x\) is \(4x\).
Now we factor \(4x\) out of the equation:
\[ 84x^2 + 16x = 4x(21x + 4) = 0 \]
Next, we set each factor equal to zero:
- \(4x = 0\)
- \(21x + 4 = 0\)
From the first factor:
\[ 4x = 0 \implies x = 0 \]
From the second factor:
\[ 21x + 4 = 0 \implies 21x = -4 \implies x = -\frac{4}{21} \]
Thus, the solutions to the equation are:
\[ x = 0 \quad \text{and} \quad x = -\frac{4}{21} \]
Therefore, the correct response is:
The solutions are \(x = 0\) and \(x = -\frac{4}{21}\).