Continuity and DifferentiabilityHard
Question
If f(x) = | x - a | + | x + b |, x ∈ R, b > a > 0. Then -
Options
A.f′(a+) = 1
B.f′(a+) = 0
C.f′(- b+) = 0
D.f′(- b+) = 1
Solution
f(x) = | x - a | + | x + b | x | x ∈ R b > a > 0 then
f(x) = | x - a | + | x + b | b > a > 0
Let a = 1, b = 2 and 2 > 1 > 0
so f(x) = | x - 1 | + | x + 2 |
f(x) =
f(x) =
f′(x) =
so that correct answer is f′(-b+) = 0
b = 2 f′(-2+) = 0
f(x) = | x - a | + | x + b | b > a > 0
Let a = 1, b = 2 and 2 > 1 > 0
so f(x) = | x - 1 | + | x + 2 |
f(x) =
f(x) =
f′(x) =
so that correct answer is f′(-b+) = 0
b = 2 f′(-2+) = 0
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