NCERT Class XI Mathematics - Relations and Functions - Solutions
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Question : 35
Total: 36
Let f be the subset of Z × Z defined by f = {(ab, a + b): a, b ∈ Z}. Is f a function from Z to Z ? Justify your answer.
Solution:
We are given f = {(ab, a + b) : a, b ∈ Z}
Let a = 1, b = – 2, we get (–2 , –1) ∈ f
Let a = – 1, b = 2, we get (– 2, 1) ∈ f
∴ f contains two ordered pairs with the same first element. Hence, f is not a function.
Let a = 1, b = – 2, we get (–2 , –1) ∈ f
Let a = – 1, b = 2, we get (– 2, 1) ∈ f
∴ f contains two ordered pairs with the same first element. Hence, f is not a function.
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