Determine whether the values -1 and 7/3 are solutions to the quadratic equation 3x^2-4x-4=3

A. Neither x= -1 nor x= 7/3 is a solution
B. Only x = -1 is a solution
C. Only x = 7/3 is a solution
D. Both x = -1 and x=7/3 are solutions

1 answer

To determine whether -1 and \( \frac{7}{3} \) are solutions to the equation \( 3x^2 - 4x - 4 = 3 \), we first simplify the equation.

Subtract 3 from both sides:

\[ 3x^2 - 4x - 4 - 3 = 0 \] \[ 3x^2 - 4x - 7 = 0 \]

Now, let's check each value:

  1. Checking \( x = -1 \):

\[ 3(-1)^2 - 4(-1) - 7 = 3(1) + 4 - 7 = 3 + 4 - 7 = 0 \]

The left side equals 0, so \( x = -1 \) is a solution.

  1. Checking \( x = \frac{7}{3} \):

Substituting \( x = \frac{7}{3} \):

\[ 3\left(\frac{7}{3}\right)^2 - 4\left(\frac{7}{3}\right) - 7 \]

Calculating \( 3\left(\frac{7}{3}\right)^2 \):

\[ 3 \cdot \frac{49}{9} = \frac{147}{9} \]

Calculating \( -4\left(\frac{7}{3}\right) \):

\[ -\frac{28}{3} = -\frac{84}{9} \]

Now we put it all together:

\[ \frac{147}{9} - \frac{84}{9} - 7 = \frac{147 - 84 - 63}{9} = \frac{0}{9} = 0 \]

The left side also equals 0, so \( x = \frac{7}{3} \) is a solution.

Since both \( x = -1 \) and \( x = \frac{7}{3} \) satisfy the equation, the answer is:

D. Both x = -1 and x = 7/3 are solutions.