Solve the quadratic equation  84x^2+16x=0

 by factoring out the GCF.

1 answer

To solve the quadratic equation 84x^2 + 16x = 0 by factoring out the greatest common factor (GCF), first, let's find the GCF of the coefficients 84 and 16.

The prime factorization of 84 is 2^2 * 3 * 7, and the prime factorization of 16 is 2^4.

The common factors are 2^2 = 4.

Now, let's factor out the GCF from the equation:

4(21x^2 + 4x) = 0

Now, we have a quadratic equation of the form ax^2 + bx = 0, where a = 21 and b = 4.

To solve this equation, we can set each factor equal to zero:

4 = 0 (This cannot be true)
21x^2 + 4x = 0

By factoring the quadratic equation further, we can now solve for x:

x(21x + 4) = 0

Setting each factor equal to zero:

x = 0
21x + 4 = 0

Solving the linear equation:

21x = -4
x = -4/21

Therefore, the solutions to the quadratic equation 84x^2 + 16x = 0, factored by the GCF, are x = 0 and x = -4/21.