questionr
Early access
Exams
Joint Entrance Examination
Mathematics
Differential Equations
Question 326
Question 326 of 490
Medium
MCQ
If
x
d
y
d
x
=
y
(
log
y
−
log
x
+
1
)
x\dfrac{dy}{dx}=y(\log y-\log x+1)
x
d
x
d
y
=
y
(
lo
g
y
−
lo
g
x
+
1
)
, the solution is:
A
y
log
x
y
=
c
x
y\log\dfrac{x}{y}=cx
y
lo
g
y
x
=
c
x
B
x
log
y
x
=
c
y
x\log\dfrac{y}{x}=cy
x
lo
g
x
y
=
cy
C
log
y
x
=
c
x
\log\dfrac{y}{x}=cx
lo
g
x
y
=
c
x
D
log
x
y
=
c
y
\log\dfrac{x}{y}=cy
lo
g
y
x
=
cy
Check answer
Press A-D to select · Enter to check
Solutions · 1
Post your solution
Official solution
With
y
=
v
x
y=vx
y
=
v
x
:
x
d
v
d
x
=
v
ln
v
⟹
∫
d
v
v
ln
v
=
∫
d
x
x
⟹
ln
(
ln
v
)
=
ln
x
+
ln
c
⟹
ln
v
=
c
x
⟹
log
(
y
/
x
)
=
c
x
x\dfrac{dv}{dx}=v\ln v \implies \int\dfrac{dv}{v\ln v}=\int\dfrac{dx}{x} \implies \ln(\ln v)=\ln x+\ln c \implies \ln v=cx \implies \log(y/x)=cx
x
d
x
d
v
=
v
ln
v
⟹
∫
v
ln
v
d
v
=
∫
x
d
x
⟹
ln
(
ln
v
)
=
ln
x
+
ln
c
⟹
ln
v
=
c
x
⟹
lo
g
(
y
/
x
)
=
c
x
.
Answer the question to unlock
Previous
Next