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Let \(f(x)=x(x+1), g(x)=x^{3}+2 x^{2}+x\). (a) Simplify the following. i. \(f(x)+g(x)\) ii. \(\frac{f(x)}{g(x)}\) iii. \(\frac{g(x)}{f(x)}\) iv. \(\frac{[f(x)]^{2}}{g(x)}\) (b) Solve \(x f(x)=g(x)\).

Short Answer

Expert verified
The simplified expressions for \(f(x) + g(x)\), \(\frac{f(x)}{g(x)}\), \(\frac{g(x)}{f(x)}\), \(\frac{[f(x)]^2}{g(x)}\) are \(x^3 + 3x^2 + 2x\), \(\frac{1}{x}\), \(x\) and \(x^2 + 2x + 1\) respectively. The solutions to the equation \(x f(x)=g(x)\) are x = 0 and x = -1.

Step by step solution

01

Simplify \(f(x) + g(x)\)

Begin by recalling that adding functions simply translates to adding respective terms. \(f(x) + g(x) = x(x+1) + (x^3 + 2x^2 + x) = x^3 + 3x^2 + 2x\)
02

Simplify \(\frac{f(x)}{g(x)}\) and \(\frac{g(x)}{f(x)}\)

The division operation in this context means that the function in the numerator is divided by the function in the denominator. i. \(\frac{f(x)}{g(x)} = \frac{x(x+1)}{x^3 + 2x^2 + x} = \frac{x(x+1)}{x(x^2 + 2x + 1)} = \frac{1}{x}\) as the \(x(x+1)\) are canceled out. ii. \(\frac{g(x)}{f(x)} = \frac{x^3 + 2x^2 + x}{x(x+1)} = \frac{x^3 + 2x^2 + x}{x(x^2 + x)} = x\) as we can divide the numerator and the denominator by \(x(x+1)\)
03

Simplify \(\frac{[f(x)]^2}{g(x)}\)

\(\frac{[f(x)]^2}{g(x)} = \frac{(x^2 + 2x + 1)^2}{x^3 + 2x^2 + x} = \frac{(x^2 + 2x + 1)^2}{x(x^2 + 2x + 1)} = (x^2 + 2x + 1)\) as we can divide the numerator and the denominator by \(x(x^2 + 2x + 1)\)
04

Solve \(x f(x)=g(x)\)

We'll equate \(x f(x)\) to \(g(x)\) and proceed to find the roots of the equation. \(x (x(x+1)) = x^3 + 2x^2 + x = 0\). This reduces to a quadratic equation and can be solved as follows: \(x^2 + x = 2x^2 + 2x\). Rearranging terms, we get x^2 + x = 0 so x(x + 1) = 0. Therefore, the solutions are x = 0 and x = -1.

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Key Concepts

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

Function Operations
Understanding function operations allows us to manipulate functions in various ways. In the context of calculus problems such as the exercise provided, operations include addition and division of functions.

For instance, to add functions like \(f(x)\) and \(g(x)\), we simply add the corresponding terms. This is what we see when \(f(x)\) is added to \(g(x)\) resulting in \(x^3 + 3x^2 + 2x\). It's a process of combining like terms, very much akin to standard polynomial addition.

Division of functions, however, is a bit more intricate. It involves rewriting the numerator and denominator so that common terms can be canceled out. In the given exercise, when dividing \(f(x)\) by \(g(x)\), we notice that the term \(x(x+1)\) appears in both the numerator and the denominator, allowing us to simplify the expression to \(\frac{1}{x}\).
Simplifying Expressions
Simplifying mathematical expressions is a cornerstone of algebra and calculus. The goal here is to reduce complex equations to their simplest forms for ease of understanding and solving. It entails combining like terms, factoring, expanding expressions, and canceling out common factors.

In our textbook example, the expression \(\frac{[f(x)]^2}{g(x)}\) was simplified to \((x^2 + 2x + 1)\) by canceling the common factor, which in this case is \(x(x^2 + 2x + 1)\). This is a great demonstration of simplifying expressions; it's all about recognizing patterns and reducing computation whenever possible.
Polynomial Division
Polynomial division can often seem daunting, but it is just an extension of basic division we use in arithmetic, applied to polynomials. When dividing one polynomial by another, we are looking for how many times the divisor can 'fit' into the dividend, or in other words, what multiple of the divisor gives us the dividend.

The step-by-step solution offered for the exercise includes an example of polynomial division where \(g(x)\) is divided by \(f(x)\). Once both functions are expressed in factored form, it's clearer to see the common terms that can be divided out, leaving us with \(x\) as the simplified expression for \(\frac{g(x)}{f(x)}\). Understanding this process is critical for solving complex calculus problems that involve polynomial functions.
Solving Equations
Solving equations is the process of finding the values, called roots, that make the equation true. For linear equations, this involves isolating the variable on one side of the equation. However, in the context of polynomial equations, which often appear in calculus problems, this might involve factoring and using the Zero Product Property.

In the exercise, to solve the equation \(x f(x) = g(x)\), we first need to express both sides as polynomials and then equate them to zero. Once in this form, we can factor the equation and find the values of \(x\) that satisfy the conditions. For the given problem, the roots came out to be \(x = 0\) and \(x = -1\), which are where the function intersects the x-axis on a graph.

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Most popular questions from this chapter

Let \(j(x)=10\left(x^{-2}+2 x^{2}\right)^{3}\). Give two possible decompositions of \(j(x)\) such that \(j(x)=f(g(h(x)))\). None of the functions \(f, g\), and \(h\) should be the identity function.

The Cambridge Widget Company is producing widgets. The xed costs for the company (costs for rent, equipment, etc.) are $$\$ 20,000.$$ This means that before any widgets are produced, the company must spend $$\$ 20,000.$$ Suppose that each widget produced costs the company an additional $$\$ 10 .$$ Let \(x\) equal the number of widgets the company produced. (a) Write a total cost function, \(C(x)\), that gives the cost of producing \(x\) widgets. (Check that your function works, e.g., check that \(C(1)=20,010\) and \(C(2)=20,020 .)\) Graph \(C(x)\). (b) At what rate is the total cost increasing with the production of each widget? In other words, nd \(\Delta C / \Delta x\). (c) Suppose the company sells widgets for $$\$ 50$$ each. Write a revenue function, \(R(x)\), that tells us the revenue received from selling \(x\) widgets. Graph \(R(x)\). (d) Pro \(\mathrm{t}=\) total revenue \(-\) total cost, so the pro \(\mathrm{t}\) function, \(P(x)\), which tells us the pro \(\mathrm{t}\) the company gets by producing and selling \(x\) widgets, can be found by computing \(R(x)-C(x) .\) Write the pro \(\mathrm{t}\) function and graph it. (e) Find \(P(400)\) and \(P(700)\); interpret your answers. Find \(P(401)\) and \(P(402) .\) By how much does the pro t increase for each additional widget sold? Is \(\Delta P / \Delta x\) constant for all values of \(x\) ? (f) How many widgets must the company sell in order to break even? (Breaking even means that the pro \(\mathrm{t}\) is \(0 ;\) the total cost is equal to the total revenue.) (g) Suppose the Cambridge Widget Company has the equipment to produce at maximum 1200 widgets. Then the domain of the pro \(\mathrm{t}\) function is all integers \(x\) where \(0 \leq x \leq 1200\). What is the range? How many widgets should be produced and sold in order to maximize the company s pro ts?

Find functions \(f, g\), and \(h\) such that \(k(x)=f(g(h(x)))\) and \(f(x) \neq x, g(x) \neq x\), and \(h(x) \neq x\). \(k(x)=\sqrt{\left(x^{2}+1\right)^{3}+5}\)

A photocopying shop has a xed cost of operation of $$\$ 4000$$ per month. In addition, it costs them $$\$ 0.01$$ per page they copy. They charge customers $$\$ 0.07$$ per page. (a) Write a formula for \(R(x)\), the shop s monthly revenue from making \(x\) copies. (b) Write a formula for \(C(x)\), the shop s monthly costs from making \(x\) copies. (c) Write a formula for \(P(x)\), the shop s monthly pro t (or loss if negative) from making \(x\) copies. Pro \(\mathrm{t}\) is computed by subtracting total costs from the total revenue. (d) How many copies must they make per month in order to break even? Breaking even means that the pro \(t\) is zero; the total costs and total revenue are equal. (e) Sketch \(C(x), R(x)\), and \(P(x)\) on the same set of axes and label the break-even point. (f) Find a formula for \(A(x)\), the shop s average cost per copy. (g) Make a table of \(A(x)\) for \(x=0,1,10,100,1000,10000\). (h) Sketch a graph of \(A(x)\).

Let \(f(x) = 2 x^{2}, g(x) = x+1\), and \(h(x) = \frac{1}{x}\) . If what is written is an expression, simplify it. If it is an equation, solve it. $$ f(g(x))=10 $$

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