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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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Most popular questions from this chapter

A suspension bridge with weight uniformly distributed along its length has twin towers that extend 75 meters above the road surface and are 400 meters apart. The cables are parabolic in shape and are suspended from the tops of the towers. The cables touch the road surface at the center of the bridge. Find the height of the cables at a point 100 meters from the center. (Assume that the road is level.

A linear function is given. (a) Find the slope and y-intercept of each function. (b) Use the slope and y-intercept to graph each function. (c) What is the average rate of change of each function? (d) Determine whether each function is increasing, decreasing, or constant. $$ p(x)=-x+6 $$

(a) find the vertex and the axis of symmetry of each quadratic function, and determine whether the graph is concave up or concave down. (b) Find the y-intercept and the \(x\) -intercepts, if any. (c) Use parts (a) and (b) to graph the function. (d) Find the domain and the range of the quadratic function. (e) Determine where the quadratic function is increasing and where it is decreasing. (f) Determine where \(f(x)>0\) and where \(f(x)<0\) \(f(x)=4 x^{2}-2 x+1\)

An accepted relationship between stopping distance \(d\) (in feet), and the speed \(v\) of a car (in \(\mathrm{mph}\) ), is \(d=1.1 v+0.06 v^{2}\) on dry, level concrete. (a) How many feet will it take a car traveling \(45 \mathrm{mph}\) to stop on dry, level concrete? (b) If an accident occurs 200 feet ahead of you, what is the maximum speed you can be traveling to avoid being involved?

Use the fact that a quadratic function of the form \(f(x)=a x^{2}+b x+c\) with \(b^{2}-4 a c>0\) may also be written in the form \(f(x)=a\left(x-r_{1}\right)\left(x-r_{2}\right),\) where \(r_{1}\) and \(r_{2}\) are the \(x\) -intercepts of the graph of the quadratic function. (a) Find quadratic functions whose \(x\) -intercepts are -3 and 1 with \(a=1 ; a=2 ; a=-2 ; a=5\) (b) How does the value of \(a\) affect the intercepts? (c) How does the value of \(a\) affect the axis of symmetry? (d) How does the value of \(a\) affect the vertex? (e) Compare the \(x\) -coordinate of the vertex with the midpoint of the \(x\) -intercepts. What might you conclude?

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