Question
upstudy study bank question image url

\( \left. \begin{array} { l } { y = 3 x ^ { 2 } - 2 x - 8 \ldots } \\ { y = 5 x - 7 \ldots } \end{array} \right. \)

Ask by Vaughan Cook. in South Africa
Feb 04,2025

Real Tutor Solution

Tutor-Verified Answer

Answer

The solutions to the system of equations are: 1. \( \left( \frac{7 + \sqrt{61}}{6}, \frac{-7 + 5\sqrt{61}}{6} \right) \) 2. \( \left( \frac{7 - \sqrt{61}}{6}, \frac{-7 - 5\sqrt{61}}{6} \right) \)

Solution

Solve the system of equations by following steps: - step0: Solve using the substitution method: \(\left\{ \begin{array}{l}y=3x^{2}-2x-8\\y=5x-7\end{array}\right.\) - step1: Substitute the value of \(y:\) \(3x^{2}-2x-8=5x-7\) - step2: Move the expression to the left side: \(3x^{2}-2x-8-\left(5x-7\right)=0\) - step3: Subtract the terms: \(3x^{2}-7x-1=0\) - step4: Solve using the quadratic formula: \(x=\frac{7\pm \sqrt{\left(-7\right)^{2}-4\times 3\left(-1\right)}}{2\times 3}\) - step5: Simplify the expression: \(x=\frac{7\pm \sqrt{\left(-7\right)^{2}-4\times 3\left(-1\right)}}{6}\) - step6: Simplify the expression: \(x=\frac{7\pm \sqrt{61}}{6}\) - step7: Separate into possible cases: \(\begin{align}&x=\frac{7+\sqrt{61}}{6}\\&x=\frac{7-\sqrt{61}}{6}\end{align}\) - step8: Evaluate the logic: \(x=\frac{7+\sqrt{61}}{6}\cup x=\frac{7-\sqrt{61}}{6}\) - step9: Rearrange the terms: \(\left\{ \begin{array}{l}x=\frac{7+\sqrt{61}}{6}\\y=3x^{2}-2x-8\end{array}\right.\cup \left\{ \begin{array}{l}x=\frac{7-\sqrt{61}}{6}\\y=3x^{2}-2x-8\end{array}\right.\) - step10: Calculate: \(\left\{ \begin{array}{l}x=\frac{7+\sqrt{61}}{6}\\y=\frac{-7+5\sqrt{61}}{6}\end{array}\right.\cup \left\{ \begin{array}{l}x=\frac{7-\sqrt{61}}{6}\\y=-\frac{7+5\sqrt{61}}{6}\end{array}\right.\) - step11: Check the solution: \(\left\{ \begin{array}{l}x=\frac{7+\sqrt{61}}{6}\\y=\frac{-7+5\sqrt{61}}{6}\end{array}\right.\cup \left\{ \begin{array}{l}x=\frac{7-\sqrt{61}}{6}\\y=-\frac{7+5\sqrt{61}}{6}\end{array}\right.\) - step12: Rewrite: \(\left(x,y\right) = \left(\frac{7+\sqrt{61}}{6},\frac{-7+5\sqrt{61}}{6}\right)\cup \left(x,y\right) = \left(\frac{7-\sqrt{61}}{6},-\frac{7+5\sqrt{61}}{6}\right)\) To solve the system of equations given by: 1. \( y = 3x^2 - 2x - 8 \) 2. \( y = 5x - 7 \) we can set the two equations equal to each other since they both equal \( y \): \[ 3x^2 - 2x - 8 = 5x - 7 \] Now, let's rearrange this equation to bring all terms to one side: \[ 3x^2 - 2x - 5x - 8 + 7 = 0 \] This simplifies to: \[ 3x^2 - 7x - 1 = 0 \] Next, we can use the quadratic formula to find the values of \( x \): \[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \] where \( a = 3 \), \( b = -7 \), and \( c = -1 \). Calculating the discriminant: \[ b^2 - 4ac = (-7)^2 - 4 \cdot 3 \cdot (-1) = 49 + 12 = 61 \] Now substituting back into the quadratic formula: \[ x = \frac{7 \pm \sqrt{61}}{6} \] This gives us two possible values for \( x \): 1. \( x_1 = \frac{7 + \sqrt{61}}{6} \) 2. \( x_2 = \frac{7 - \sqrt{61}}{6} \) Next, we substitute these \( x \) values back into one of the original equations to find the corresponding \( y \) values. Using \( y = 5x - 7 \): For \( x_1 \): \[ y_1 = 5\left(\frac{7 + \sqrt{61}}{6}\right) - 7 = \frac{35 + 5\sqrt{61}}{6} - 7 = \frac{35 + 5\sqrt{61} - 42}{6} = \frac{-7 + 5\sqrt{61}}{6} \] For \( x_2 \): \[ y_2 = 5\left(\frac{7 - \sqrt{61}}{6}\right) - 7 = \frac{35 - 5\sqrt{61}}{6} - 7 = \frac{35 - 5\sqrt{61} - 42}{6} = \frac{-7 - 5\sqrt{61}}{6} \] Thus, the solutions to the system of equations are: 1. \( \left( \frac{7 + \sqrt{61}}{6}, \frac{-7 + 5\sqrt{61}}{6} \right) \) 2. \( \left( \frac{7 - \sqrt{61}}{6}, \frac{-7 - 5\sqrt{61}}{6} \right) \)

Reviewed and approved by the UpStudy tutoring team

error msg
Explain
Simplify this solution

Mind Expander

To solve the system of equations represented by \( y = 3x^2 - 2x - 8 \) and \( y = 5x - 7 \), you can set the two equations equal to each other, which gives you: \[ 3x^2 - 2x - 8 = 5x - 7. \] Rearranging this leads to the quadratic equation: \[ 3x^2 - 7x - 1 = 0. \] Now you can either factor, complete the square, or use the quadratic formula to find the values of \( x \). In real-world applications, solving systems of equations like this can represent various scenarios, like finding the intersection points of a parabolic trajectory (the first equation) and a linear path (the second equation). These intersections could represent points in time or space where two different moving objects meet. One common mistake when solving such problems is neglecting to carefully simplify the equation after combining like terms. Take your time to ensure every term is correctly calculated, and always double-check your work before concluding the values of \( x \).

Related Questions

Latest Algebra Questions

Try Premium now!
Try Premium and ask Thoth AI unlimited math questions now!
Maybe later Go Premium
Study can be a real struggle
Why not UpStudy it?
Select your plan below
Premium

You can enjoy

Start now
  • Step-by-step explanations
  • 24/7 expert live tutors
  • Unlimited number of questions
  • No interruptions
  • Full access to Answer and Solution
  • Full Access to PDF Chat, UpStudy Chat, Browsing Chat
Basic

Totally free but limited

  • Limited Solution
Welcome to UpStudy!
Please sign in to continue the Thoth AI Chat journey
Continue with Email
Or continue with
By clicking “Sign in”, you agree to our Terms of Use & Privacy Policy