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Which of the following is one-one function defined from R to R(A) f(x) = |x|(B) f(x) = cos x(C) f(x) = ex(D) f(x) = x2 |
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Answer» Answer is (C) f(x) = ex Let x, y ∈ R are such that f(x) = f(y) ⇒ ex = ey ⇒ x loge e = y loge e ⇒ x = y f(x) = f(y) ⇒ x = y [∵ loge e = 1] f is one-one function ∀ x, y ∈ R |
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