4x-2 = x^2-3x-8
Understand the Problem
This question requires solving a quadratic equation. The goal is to find the values of 'x' that satisfy the equation 4x - 2 = x^2 - 3x - 8. This involves rearranging the equation into the standard quadratic form (ax^2 + bx + c = 0) and then solving for x, which can be done by factoring, completing the square, or using the quadratic formula.
Answer
$x = \frac{7 + \sqrt{73}}{2}$ and $x = \frac{7 - \sqrt{73}}{2}$
Answer for screen readers
$x = \frac{7 + \sqrt{73}}{2}$ and $x = \frac{7 - \sqrt{73}}{2}$
Steps to Solve
- Rearrange the equation
Move all terms to one side of the equation to set it equal to zero. This puts the quadratic equation in standard form ($ax^2 + bx + c = 0$).
$4x - 2 = x^2 - 3x - 8$
Subtract $4x$ from both sides: $-2 = x^2 - 7x - 8$
Add $2$ to both sides: $0 = x^2 - 7x - 6$
- Apply the quadratic formula
Since the quadratic equation $x^2 - 7x - 6 = 0$ does not factor easily, we use the quadratic formula to find the solutions for $x$. The quadratic formula is:
$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$
In our equation, $a = 1$, $b = -7$, and $c = -6$. Plugging these values into the quadratic formula gives:
$x = \frac{-(-7) \pm \sqrt{(-7)^2 - 4(1)(-6)}}{2(1)}$
- Simplify the expression
Simplify the expression inside the square root and the rest of the equation:
$x = \frac{7 \pm \sqrt{49 + 24}}{2}$
$x = \frac{7 \pm \sqrt{73}}{2}$
- State the solutions
The two solutions for $x$ are:
$x = \frac{7 + \sqrt{73}}{2}$ and $x = \frac{7 - \sqrt{73}}{2}$
$x = \frac{7 + \sqrt{73}}{2}$ and $x = \frac{7 - \sqrt{73}}{2}$
More Information
The solutions are irrational numbers because the discriminant ($b^2 - 4ac = 73$) is not a perfect square.
Tips
- Incorrectly identifying the coefficients a, b, and c.
- Making errors when substituting values into the quadratic formula.
- Arithmetic errors when simplifying the expression, especially under the square root.
- Forgetting the $\pm$ sign, which leads to only one solution instead of two.
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