The quadratic equation $x^2 + bx + c = 0$ has distinct roots. If 2 is subtract from each root then result are the reciprocal of the original root. The value of $(b^2 + c^2)$ is:
Step-by-Step Solution
Key Concept: Quadratic equations with conditions on roots
Step 1: Define the roots and apply Vieta's formulas.
Let the roots of the quadratic equation $x^2 + bx + c = 0$ be $\alpha$ and $\beta$.
By Vieta's formulas:
$$\alpha + \beta = -b$$
$$\alpha\beta = c$$
Step 2: Translate the given condition into equations.
We are told that when 2 is subtracted from each root, the results are the reciprocals of the original roots. This gives us:
$$\alpha - 2 = \frac{1}{\alpha}$$
$$\beta - 2 = \frac{1}{\beta}$$
Step 3: Simplify the condition for $\alpha$.
Starting with $\alpha - 2 = \frac{1}{\alpha}$, multiply both sides by $\alpha$:
$$\alpha^2 - 2\alpha = 1$$
$$\alpha^2 - 2\alpha - 1 = 0$$
Step 4: Simplify the condition for $\beta$.
Similarly, from $\beta - 2 = \frac{1}{\beta}$:
$$\beta^2 - 2\beta = 1$$
$$\beta^2 - 2\beta - 1 = 0$$
Step 5: Recognize that both roots satisfy the same equation.
Since both $\alpha$ and $\beta$ satisfy the equation $x^2 - 2x - 1 = 0$, they must be the roots of this equation.
Comparing $x^2 - 2x - 1 = 0$ with the original form $x^2 + bx + c = 0$:
$$b = -2$$
$$c = -1$$
Step 6: Calculate $b^2 + c^2$.
$$b^2 + c^2 = (-2)^2 + (-1)^2 = 4 + 1 = 5$$
**Final Answer:** The value of $b^2 + c^2$ is $\boxed{5}$, which corresponds to **Option 4**.
Correct Answer: 4