Use the discriminant to determine the number of real solutions of 3x2+6x−42=0 .(1 point)

real solution(s)

1 answer

To determine the number of real solutions for the quadratic equation \(3x^2 + 6x - 42 = 0\), we first identify the coefficients \(a\), \(b\), and \(c\):

  • \(a = 3\)
  • \(b = 6\)
  • \(c = -42\)

Next, we use the discriminant formula, which is given by:

\[ D = b^2 - 4ac \]

Substituting in the values of \(a\), \(b\), and \(c\):

\[ D = 6^2 - 4(3)(-42) \]

Calculating \(b^2\):

\[ 6^2 = 36 \]

Now calculating \(4ac\):

\[ 4(3)(-42) = -504 \]

So, the discriminant becomes:

\[ D = 36 - (-504) = 36 + 504 = 540 \]

Now we analyze the value of the discriminant \(D\):

  • If \(D > 0\), there are two distinct real solutions.
  • If \(D = 0\), there is one real solution (a repeated solution).
  • If \(D < 0\), there are no real solutions.

Since \(D = 540\) is greater than 0, we conclude that the equation \(3x^2 + 6x - 42 = 0\) has two distinct real solutions.