7. Determine whether each of these functions is a bijection from R to R.a) f (x) = −3x + 4 b) f (x) = −3x2 + 7 c) f (x) = (x + 1)/(x + 2) d) f (x) = x5 + 1
Question
- Determine whether each of these functions is a bijection from R to R.a) f (x) = −3x + 4 b) f (x) = −3x2 + 7 c) f (x) = (x + 1)/(x + 2) d) f (x) = x5 + 1
Solution
a) f(x) = -3x + 4 is a bijection. It is both injective and surjective. It is injective because for every x1 ≠ x2, f(x1) ≠ f(x2). It is surjective because for every y in R, there exists an x in R such that f(x) = y.
b) f(x) = -3x^2 + 7 is not a bijection. It is not injective because for x1 ≠ x2, f(x1) can be equal to f(x2). For example, f(1) = f(-1). It is not surjective because for y > 7, there does not exist an x in R such that f(x) = y.
c) f(x) = (x + 1)/(x + 2) is not a bijection. It is injective because for every x1 ≠ x2, f(x1) ≠ f(x2). However, it is not surjective because
Similar Questions
Determine whether the following functions are bijective.(a) f : R → R, with y = f (x) = 3x + 52(b) f : R → R, with y = f (x) = (2x − 7)2(c) f : R → R, with y = f (x) = √3x − 1
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Let A=7,8,9 and B=7,8,9 and f is onto from A to B, then which of the following is correct?*f is bijectivef is surjectivef may or may not be bijectivef is into function
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