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Explain why the inequality \(x^{2}-x+1<0\) has the empty set as the solution set.

Short Answer

Expert verified
The inequality \(x^2 - x + 1 < 0\) has no solutions because the quadratic function is always positive.

Step by step solution

01

Analyze the quadratic function y = x² - x + 1

Consider the quadratic function given by the expression \(y = x^2 - x + 1\). This inequality requires us to determine where this function is less than zero.
02

Find the discriminant

The discriminant of a quadratic equation \(ax^2 + bx + c = 0\) is given by \(D = b^2 - 4ac\). For our equation \(x^2 - x + 1 = 0\), we have \(a = 1\), \(b = -1\), and \(c = 1\). Therefore, the discriminant is: \[ D = (-1)^2 - 4(1)(1) = 1 - 4 = -3 \]
03

Interpret the discriminant

A negative discriminant (\(D < 0\)) means that the quadratic equation has no real roots, which implies that the quadratic function \(y = x^2 - x + 1\) does not intersect the x-axis. This indicates that the quadratic function is always either above or below the x-axis.
04

Determine the sign of the quadratic function

To determine whether the parabola opens upwards or downwards, look at the coefficient of the \(x^2\) term. Since the coefficient is positive (\(a = 1 > 0\)), the parabola opens upwards. Therefore, \(y = x^2 - x + 1\) is always greater than zero.
05

Conclusion

Since the quadratic function \(y = x^2 - x + 1\) is always greater than zero, there are no values of x for which \(x^2 - x + 1 < 0\). Thus, the solution set is empty.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

discriminant
Understanding the concept of the discriminant is crucial for solving quadratic inequalities. The discriminant is a special value that can be calculated from the coefficients of a quadratic equation.In our case, the quadratic equation was given by y = x^{2}-x + 1. The standard form of a quadratic equation is ax^2 + bx + c = 0, where a, b, and c are the coefficients.The formula to find the discriminant (D) is: b^2 - 4ac.Let's substitute the coefficients from our equation: a = 1, b = -1, and c = 1. Plugging these values into the formula gives D = (-1)^2 - 4(1)(1) = 1 - 4 = -3.The discriminant helps us determine the nature of the roots (solutions) of the equation.In this case, D = -3, which is less than zero. A negative discriminant means that the quadratic equation has no real roots.This also suggests that the graph of the quadratic function does not intersect the x-axis.
quadratic function
A quadratic function is any function that can be written in the form ax^2 + bx + c, where a, b, and c are constants, and x is the variable.Quadratic functions form a parabola when graphed.To understand quadratic functions better, it's helpful to understand their graph.The direction in which the parabola opens is determined by the coefficient a. If a > 0, the parabola opens upwards.If a < 0, the parabola opens downwards.In the case of our function y = x^2 - x + 1, the coefficient a = 1 is positive.So, the parabola opens upwards.Given that we already determined that the discriminant is negative (indicating no real roots), this means our parabola does not touch or cross the x-axis.This tells us something about the inequality x^2 - x + 1 < 0 that we're trying to solve. Since the parabola always lies above the x-axis and opens upwards, our quadratic function y = x^2 - x + 1 is always greater than zero.
solution set
The solution set is where we find the values of x that satisfy the given inequality. For the inequality x^2 - x + 1 < 0, we need values where the quadratic function is less than zero. However, from the analysis of the quadratic function and its discriminant, we see that this particular function y = x^2 - x + 1 is always positive for all real numbers.That means there are no values of x for which the quadratic function becomes less than zero.So the inequality x^2 - x + 1 < 0 has no solutions in the real number system.Therefore, the solution set is empty.Understanding the solution set of quadratic inequalities is essential in identifying where a function's values lie relative to a given threshold—especially in advanced mathematical problems like optimization and modeling.

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