Completing the Square & the Quadratic Formula Quick Check

4 of 54 of 5 Items
Question
Which of the following is a solution to the quadratic equation 2x2−5x=6
? Assume that the solution has been rounded to the nearest hundredth, if applicable.(1 point)
Responses

x=1.03
x equals 1.03

x=0.89
x equals 0.89

x=−1.03
x equals negative 1.03

x=−0.89

1 answer

To solve the quadratic equation \(2x^2 - 5x = 6\), we first rearrange it into standard form:

\[ 2x^2 - 5x - 6 = 0 \]

Next, we can either complete the square or use the quadratic formula. Here, we'll use the quadratic formula:

\[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \]

In our equation, \(a = 2\), \(b = -5\), and \(c = -6\).

Now, we calculate the discriminant \(b^2 - 4ac\):

\[ b^2 - 4ac = (-5)^2 - 4(2)(-6) = 25 + 48 = 73 \]

Now plug in the values into the quadratic formula:

\[ x = \frac{-(-5) \pm \sqrt{73}}{2(2)} \]

This simplifies to:

\[ x = \frac{5 \pm \sqrt{73}}{4} \]

Now we need to calculate both potential solutions:

Calculating \( \sqrt{73} \): \[ \sqrt{73} \approx 8.544 \]

Finding the two solutions:

  1. First solution: \[ x_1 = \frac{5 + 8.544}{4} = \frac{13.544}{4} \approx 3.386 \]

  2. Second solution: \[ x_2 = \frac{5 - 8.544}{4} = \frac{-3.544}{4} \approx -0.886 \]

Rounding to the nearest hundredth:

  • \(x_1 \approx 3.39\)
  • \(x_2 \approx -0.89\)

Thus, among the choices provided:

  • x = -0.89 is a solution.

Therefore, the correct response is:

x = -0.89.