Given differential equation, sin ( 2 x 2 ) ln ( t a n x 2 ) d y + ( 4 x y − 4 2 x s i n ( x 2 − π 4 ) ) d x = 0 \sin \left(2{x}^{2}\right)\ln \left(tan{x}^{2}\right)dy + \left(4xy - 4\sqrt{2}xsin\left({x}^{2} - \dfrac{\pi}{4}\right)\right)dx = 0 sin ( 2 x 2 ) ln ( t an x 2 ) d y + ( 4 x y − 4 2 x s in ( x 2 − 4 π ) ) d x = 0
⇒ ln ( t a n x 2 ) d y + 4 x y d x sin ( 2 x 2 ) − 4 2 x s i n ( x 2 − π 4 ) sin ( 2 x 2 ) d x = 0 ⇒ \ln \left(tan{x}^{2}\right)dy + \dfrac{4xydx}{\sin \left(2{x}^{2}\right)} - \dfrac{4\sqrt{2}xsin\left({x}^{2} - \dfrac{\pi}{4}\right)}{\sin \left(2{x}^{2}\right)}dx = 0 ⇒ ln ( t an x 2 ) d y + sin ( 2 x 2 ) 4 x y d x − sin ( 2 x 2 ) 4 2 x s in ( x 2 − 4 π ) d x = 0
⇒ d ( y ⋅ ln ( t a n x 2 ) ) − 4 2 x ( s i n x 2 − c o s x 2 ) 2 ( 2 s i n x 2 c o s x 2 ) d x = 0 ⇒ d\left(y \cdot \ln \left(tan{x}^{2}\right)\right) - 4\sqrt{2}x\dfrac{\left(sin{x}^{2} - cos{x}^{2}\right)}{\sqrt{2}\left(2sin{x}^{2}cos{x}^{2}\right)}dx = 0 ⇒ d ( y ⋅ ln ( t an x 2 ) ) − 4 2 x 2 ( 2 s in x 2 cos x 2 ) ( s in x 2 − cos x 2 ) d x = 0
⇒ d ( y l n ( t a n x 2 ) ) − 4 x ( s i n x 2 − c o s x 2 ) ( s i n x 2 + cos 2 x ) 2 − 1 d x = 0 ⇒ d\left(yln\left(tan{x}^{2}\right)\right) - \dfrac{4x\left(sin{x}^{2} - cos{x}^{2}\right)}{{\left(sin{x}^{2} + \cos^{2}x\right)}^{2} - 1}dx = 0 ⇒ d ( y l n ( t an x 2 ) ) − ( s in x 2 + cos 2 x ) 2 − 1 4 x ( s in x 2 − cos x 2 ) d x = 0
Now integrating both side,
⇒ ∫ d ( y l n ( t a n x 2 ) ) − ∫ 4 x ( s i n x 2 − c o s x 2 ) ( s i n x 2 + cos 2 x ) 2 − 1 d x = ∫ 0 ⇒ ∫ d\left(yln\left(tan{x}^{2}\right)\right) - ∫ \dfrac{4x\left(sin{x}^{2} - cos{x}^{2}\right)}{{\left(sin{x}^{2} + \cos^{2}x\right)}^{2} - 1}dx = ∫ 0 ⇒ ∫ d ( y l n ( t an x 2 ) ) − ∫ ( s in x 2 + cos 2 x ) 2 − 1 4 x ( s in x 2 − cos x 2 ) d x = ∫ 0
Now let s i n x 2 + cos 2 x = t ⇒ − 2 x ( s i n x 2 − cos 2 x ) = d t sin{x}^{2} + \cos^{2}x = t ⇒ - 2x\left(sin{x}^{2} - \cos^{2}x\right) = dt s in x 2 + cos 2 x = t ⇒ − 2 x ( s in x 2 − cos 2 x ) = d t
⇒ ∫ d ( y l n ( t a n x 2 ) ) + 2 ∫ d t t 2 − 1 = ∫ 0 ⇒ ∫ d\left(yln\left(tan{x}^{2}\right)\right) + 2 ∫ \dfrac{dt}{{t}^{2} - 1} = ∫ 0 ⇒ ∫ d ( y l n ( t an x 2 ) ) + 2 ∫ t 2 − 1 d t = ∫ 0
⇒ y l n ( t a n x 2 ) + 2 ⋅ 1 2 ln ∣ t − 1 t + 1 ∣ = c ⇒ yln\left(tan{x}^{2}\right) + 2 \cdot \dfrac{1}{2}\ln \left|\dfrac{t - 1}{t + 1}\right| = c ⇒ y l n ( t an x 2 ) + 2 ⋅ 2 1 ln t + 1 t − 1 = c
y l n ( t a n x 2 ) + ln ( s i n x 2 + c o s x 2 − 1 s i n x 2 + c o s x 2 + 1 ) = c yln\left(tan{x}^{2}\right) + \ln \left(\dfrac{sin{x}^{2} + cos{x}^{2} - 1}{sin{x}^{2} + cos{x}^{2} + 1}\right) = c y l n ( t an x 2 ) + ln ( s in x 2 + cos x 2 + 1 s in x 2 + cos x 2 − 1 ) = c
Put y = 1 and x = π 6 x = \sqrt{\dfrac{\pi}{6}} x = 6 π
1 ln ( 1 3 ) + l n ( 1 2 + 3 2 − 1 ) ( 1 2 + 3 2 + 1 ) = c 1\ln \left(\dfrac{1}{\sqrt{3}}\right) + ln\dfrac{\left(\dfrac{1}{2} + \dfrac{\sqrt{3}}{2} - 1\right)}{\left(\dfrac{1}{2} + \dfrac{\sqrt{3}}{2} + 1\right)} = c 1 ln ( 3 1 ) + l n ( 2 1 + 2 3 + 1 ) ( 2 1 + 2 3 − 1 ) = c
Now at x = π 3 x = \sqrt{\dfrac{\pi}{3}} x = 3 π
⇒ y ( l n 3 ) + l n ( 3 2 + 1 2 − 1 ) ( 3 2 + 1 2 + 1 ) = ln ( 1 3 ) + ln ( 3 − 1 3 + 3 ) ⇒ y\left(ln\sqrt{3}\right) + ln\dfrac{\left(\dfrac{\sqrt{3}}{2} + \dfrac{1}{2} - 1\right)}{\left(\dfrac{\sqrt{3}}{2} + \dfrac{1}{2} + 1\right)} = \ln \left(\dfrac{1}{\sqrt{3}}\right) + \ln \left(\dfrac{\sqrt{3} - 1}{\sqrt{3} + 3}\right) ⇒ y ( l n 3 ) + l n ( 2 3 + 2 1 + 1 ) ( 2 3 + 2 1 − 1 ) = ln ( 3 1 ) + ln ( 3 + 3 3 − 1 )
⇒ y ( l n 3 ) = ln ( 1 3 ) < / p > < p > ⇒ y\left(ln\sqrt{3}\right) = \ln \left(\dfrac{1}{\sqrt{3}}\right)</p><p> ⇒ y ( l n 3 ) = ln ( 3 1 ) < / p >< p > ⇒ y = - 1< / p > < p > S o , ∣ y ∣ = 1 </p><p>So, \left|y\right| = 1 < / p >< p > S o , ∣ y ∣ = 1