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 can factor the equation:
\[ 84x^2 + 16x = 4x(21x + 4) = 0 \]
Setting each factor equal to zero gives us:
- \( 4x = 0 \) which simplifies to \( x = 0 \).
- \( 21x + 4 = 0 \) which simplifies to \( 21x = -4 \) and thus \( x = -\frac{4}{21} \).
Therefore, the solutions are \( x = 0 \) and \( x = -\frac{4}{21} \).
So the correct response is:
The solutions are \( x = -\frac{4}{21} \) and \( x = 0 \).