Check the injectivity and surjectivity of the following function

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 Multiple Choice QuestionsShort Answer Type

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371.

Check the injectivity and surjectivity of the following functions:
f : N → N given by f(x) : x2 



f : N → N given by
f(x) : x2 
It is seen that for x, y element of straight N, f(x) = f(y) rightwards double arrowx3 = y3 rightwards double arrowx = y
therefore  f is injective
Now,  2 element of space straight N, But there does not exist  any element x in domain N such that f(x) = x3=2
therefore  f is not surjective 
Hence, function f is injective but not surjective.

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372.

Check the injectivity and surjectivity of the following functions.

f : Z → Z given by f(x) = x2

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373.

Show that the Signum Function f : R → R, given by

                    straight f left parenthesis straight x right parenthesis space open curly brackets table row cell 1 comma space if space straight x space 0 end cell row cell 0 comma space if space straight x space 0 end cell row cell negative 1 comma space if space straight x space 0 end cell end table close curly brackets

is neither one-one nor onto

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374.

In each of the following cases, state whether the function is one-one, onto or bijective. Justify your answer.

f : R → R defined by f(x) = 3 – 4x

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375.

In each of the following cases, state whether the function is one-one, onto or bijective. Justify your answer.

f : R → R defined by f(x) = 1 + x2

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376. Let A = {1. 2. 3}. Then show that the number of relations containing (1,2) and (2. 3) which are reflexive and transitive but not symmetric is four.
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377. Let X = {1, 2, 3, 4, 5, 6, 7, 8, 9}. Let R1 be a relation in X given by R1 = {(x, y) : x – y is divisible by 3} and R2 be another relation on X given by R2 = {(x, y) : {x, y} ⊂ {1,4, 7 }} or ⊂ {2, 5, 8} or {x, y,}⊂ {3, 6, 9}}. Show that R1 = R2.
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378.

Consider the binary operation A on the set {1, 2, 3, 4, 5} defined by a ∧ b = min. {a, b}. Write the operation table of the operation ∧.

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379. Define a binary operation * on the set {0, 1, 2, 3, 4, 5} as

straight a space asterisk times space straight b space equals space open curly brackets table attributes columnalign left end attributes row cell straight a plus straight b space space space space space space space space space space space space space space space space if space straight a plus straight b less than 6 end cell row cell straight a plus straight b minus 6 space space space space space space space space space space space space if space straight a plus straight b greater or equal than 6 end cell end table close

Show that zero is the identity for this operation and each element a of the set is invertible with 6 – a being the inverse of a.
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380.

Let A = Q x Q. Let be a binary operation on A defined by (a, b) * (c, d) = (ac, ad + b).

Then

(i) Find the identify element of (A, *)
(ii) Find the invertible elements of (A, *)

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