Question
Mathematics Question on Logarithmic Differentiation
Let f:R→R be a differentiable function such that f′(x)+f(x)=0∫2f(t)dtIf f(0)=e−2, then 2f(0)−f(2) is equal to_____
Answer
The correct answer is 1.
dxdy+y=k
y⋅ex=k⋅ex+c
f(0)=e−2
⇒c=e−2−k
∴y=k+(e−2−k)e−x
now k=0∫2(k+(e−2−k)e−x)dx
⇒k=e−2−1
∴y=(e−2−1)+e−x
f(2)=2e−2−1,f(0)=e−2
2f(0)−f(2)=1