Mathematics - Application of Derivative Question with Solution | TestHub

MathematicsApplication of DerivativeMaxima-MinimaMedium2 minPYQ_2019
MathematicsMediumsingle choice

Letfx=ex-xandgx=x2-x, ∀ x ϵ R. Then the set of allx ϵ R, where the functionhx=fogxis increasing, is:

Options:

Answer:
C
Solution:

hx=fogx=egx-gx
=ex2-x-x2-x
h'x=ex2-x×2x-1-2x+1
=2x-1ex2-x-1
∵hxis increasing∴h'x≥0⇒2x-1ex2-x-1≥0
Case 1:2x-1≥0&x2-x≥0
⇒x≥12 & x∈-∞, 0∪1,∞⇒x∈1, ∞
Case 2:2x-1≤0andx2-x≤0
x<12andx∈0, 1⇒x∈0,12
∴  x∈0,12∪[1,∞)

Stream:JEESubject:MathematicsTopic:Application of DerivativeSubtopic:Maxima-Minima
⏱ 2mℹ️ Source: PYQ_2019

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