(a) Define F: z-Z by the rule F(n) = 2 - 3n, for each integer n. () Is Fone-to-one? Suppose n, and n, are any integers, such that F(n,) = F(n,). Substituting from the definition of F gives that 2 - 3n, = Solving this equation for n, and simplifying the result gives that n- Therefore, Fis one-to-one (i) Show that Fis not onto. Counterexample: Let m = For this value of m, the only number n with the property that F(n) - m is not an integer. Thus, Fis not onto. (b) Define G: R-R by the rule G(x) - 2 - 3x for each real number x. Is G onto?

Algebra & Trigonometry with Analytic Geometry
13th Edition
ISBN:9781133382119
Author:Swokowski
Publisher:Swokowski
Chapter4: Polynomial And Rational Functions
Section4.3: Zeros Of Polynomials
Problem 66E
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(a) Define F: Z → Z by the rule F(n) = 2 - 3n, for each integer n.
(i) Is F one-to-one?
Suppose n, and n, are any integers, such that F(n,) = F(n,). Substituting from the definition of F gives that 2 - 3n, =
Solving this equation for n, and simplifying the result gives that n, =
Therefore, F is one-to-one
(ii) Show that F is not onto.
Counterexample:
Let m =
. For this value of m, the only number n with the property that F(n) = m is not an integer. Thus, F is not onto.
(b) Define G: R → R by the rule G(x) = 2 - 3x for each real number x. Is G onto?
Scratch work: Let y be any real number.
On a separate piece of paper, solve the equation y = 2 - 3x for x. Enter the result-an expression in y-in the box below.
X =
(1) Is x a real number?
Sums, products, and differences of real numbers are always real numbers
, and quotients of real numbers with nonzero denominators are always real numbers
. Therefore, x is a real number
(2) Does G(y) = x?
According to the formula that defines G, when G is applied to x, x is multiplied by 3 and the result is subtracted from 2.
When the expression for x that you found above is multiplied by 3, the result is
. And when the result is subtracted from 2, you obtain
Thus, G(y) = x
Hence, there exists
a number x such that x is a real number and G(x) = y. Therefore, G is onto
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Transcribed Image Text:(a) Define F: Z → Z by the rule F(n) = 2 - 3n, for each integer n. (i) Is F one-to-one? Suppose n, and n, are any integers, such that F(n,) = F(n,). Substituting from the definition of F gives that 2 - 3n, = Solving this equation for n, and simplifying the result gives that n, = Therefore, F is one-to-one (ii) Show that F is not onto. Counterexample: Let m = . For this value of m, the only number n with the property that F(n) = m is not an integer. Thus, F is not onto. (b) Define G: R → R by the rule G(x) = 2 - 3x for each real number x. Is G onto? Scratch work: Let y be any real number. On a separate piece of paper, solve the equation y = 2 - 3x for x. Enter the result-an expression in y-in the box below. X = (1) Is x a real number? Sums, products, and differences of real numbers are always real numbers , and quotients of real numbers with nonzero denominators are always real numbers . Therefore, x is a real number (2) Does G(y) = x? According to the formula that defines G, when G is applied to x, x is multiplied by 3 and the result is subtracted from 2. When the expression for x that you found above is multiplied by 3, the result is . And when the result is subtracted from 2, you obtain Thus, G(y) = x Hence, there exists a number x such that x is a real number and G(x) = y. Therefore, G is onto Need Help? Read It
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