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Let R+ be the set of all non- negative real numbers. Show that the function f: R+ → [4,∞) given by f(x) = x2 + 4 is invertible and write the inverse of f. |
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Answer» f(x1) = f(x2) X12 + 4 = X22 + 4 x1 = x2 ∴ f (x) is one-one Let y = f(x) y = 4x + 3 x = y - 3/4 ∈R+ ∴ f (x) is onto Let f-1 (x) = y f(y) = x 4y +3 = x y = x - 3/4 ∴ f-1 : [4,8) → R+ is defined by f-1 (x) = x - 3/4 |
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