Which of the following is a solution to the quadratic equation 4x^2+2x=10

? Assume that the solution has been rounded to the nearest hundredth, if applicable.

why is this deliberately wrong x=1.04
why is this right?x=-1.85

3 answers

To determine which of the proposed solutions is correct for the quadratic equation \( 4x^2 + 2x = 10 \), we need to solve the equation first.

  1. Rearranging the equation: \[ 4x^2 + 2x - 10 = 0 \]

  2. Using the quadratic formula: The quadratic formula is given by: \[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \] where \( a = 4 \), \( b = 2 \), and \( c = -10 \).

  3. Calculating the discriminant: \[ b^2 - 4ac = 2^2 - 4(4)(-10) = 4 + 160 = 164 \]

  4. Applying the quadratic formula: \[ x = \frac{-2 \pm \sqrt{164}}{2(4)} \] \[ x = \frac{-2 \pm \sqrt{164}}{8} \] \[ \sqrt{164} \approx 12.81 \] Therefore: \[ x = \frac{-2 \pm 12.81}{8} \]

  5. Calculating the two possible values:

    • First solution: \[ x_1 = \frac{-2 + 12.81}{8} \approx \frac{10.81}{8} \approx 1.35 \]

    • Second solution: \[ x_2 = \frac{-2 - 12.81}{8} \approx \frac{-14.81}{8} \approx -1.85 \]

  6. Conclusion: The solutions are approximately \( x \approx 1.35 \) and \( x \approx -1.85 \).

From the proposed answers:

  • \( x = 1.04 \) is incorrect based on this calculation, as it does not match the calculated value of approximately \( 1.35 \).
  • \( x = -1.85 \) is correct, as it matches the calculated approximate solution.

In summary, \( x = 1.04 \) is wrong because it doesn't satisfy the equation, while \( x = -1.85 \) is a correct solution.

could you make it a little more simple

Sure! Let's break it down into simple steps to solve the equation \(4x^2 + 2x = 10\).

  1. Set the equation to zero: \[ 4x^2 + 2x - 10 = 0 \]

  2. Identify the coefficients: Here, \(a = 4\), \(b = 2\), and \(c = -10\).

  3. Use the quadratic formula: The formula is: \[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \]

  4. Calculate the discriminant (\(b^2 - 4ac\)): \[ b^2 - 4ac = 2^2 - 4(4)(-10) = 4 + 160 = 164 \]

  5. Calculate the two solutions:

    • Find \(\sqrt{164} \approx 12.81\).

    • Now plug it into the formula: \[ x = \frac{-2 \pm 12.81}{8} \]

    • First solution: \[ x_1 = \frac{-2 + 12.81}{8} \approx \frac{10.81}{8} \approx 1.35 \]

    • Second solution: \[ x_2 = \frac{-2 - 12.81}{8} \approx \frac{-14.81}{8} \approx -1.85 \]

  6. Final answers:

    • One solution is approximately 1.35.
    • The other solution is approximately -1.85.

From your options:

  • \(x = 1.04\) is incorrect.
  • \(x = -1.85\) is correct.

So, \(x = -1.85\) is the right answer!