Quadratic Equations Online Practice

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Question
Which of the following is a solution to the quadratic equation 2x2−9x=4
? Assume that the solution has been rounded to the nearest hundredth. if applicable.(1 point)
Responses

x=4.91
x equals 4.91

x=−0.77
x equals negative 0.77

x=−0.91
x equals negative 0.91

x=4.77
x equals 4.77
Remaining Attempts : 3
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1 answer

To solve the quadratic equation \(2x^2 - 9x = 4\), we first rearrange the equation into standard form:

\[ 2x^2 - 9x - 4 = 0 \]

Next, we can either factor the equation (if possible), complete the square, or use the quadratic formula:

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

In this case, \(a = 2\), \(b = -9\), and \(c = -4\).

Let's calculate the discriminant:

\[ b^2 - 4ac = (-9)^2 - 4 \cdot 2 \cdot (-4) = 81 + 32 = 113 \]

Now we will plug these values into the quadratic formula:

\[ x = \frac{-(-9) \pm \sqrt{113}}{2 \cdot 2} = \frac{9 \pm \sqrt{113}}{4} \]

Calculating \( \sqrt{113} \):

\(\sqrt{113} \approx 10.630\)

Now plug this value back into the formula:

\[ x = \frac{9 \pm 10.630}{4} \]

Calculating the two solutions:

  1. \(x = \frac{9 + 10.630}{4} = \frac{19.630}{4} \approx 4.9075 \approx 4.91\)
  2. \(x = \frac{9 - 10.630}{4} = \frac{-1.630}{4} \approx -0.4075 \approx -0.41\) (not listed in your options)

Since only one choice rounds to the nearest hundredth, the solution to the quadratic equation \(2x^2 - 9x = 4\) is:

x = 4.91.