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Gwen was asked to solve the equation 3x^2 - 20 = 7. What is the correct solution?

A: x = -3

B: x = -3, x = 3

C: x = 9, x = -9

D: x = 3

1 answer

To solve the equation \( 3x^2 - 20 = 7 \), we first need to rearrange it into standard form.

  1. Start by adding 20 to both sides: \[ 3x^2 - 20 + 20 = 7 + 20 \] This simplifies to: \[ 3x^2 = 27 \]

  2. Next, divide both sides by 3: \[ x^2 = \frac{27}{3} \] This simplifies to: \[ x^2 = 9 \]

  3. Now, take the square root of both sides: \[ x = \pm 3 \]

Thus, the solutions are \( x = 3 \) and \( x = -3 \).

The correct answer is B: x = -3, x = 3.