Now, apply operation C2→C2−C1 and C3→C3−C1, we get (2‌sin‌2‌x+cos‌2‌x)
|
1
0
0
sin‌2‌x
cos‌2‌x−sin‌2‌x
0
sin‌2‌x
0
cos‌2‌x−sin‌2‌x
|=0
Expanding along R1, we get (2‌sin‌2‌x+cos‌2‌x)(cos‌2‌x−sin‌2‌x)2=0 ⇒‌‌2‌sin‌2‌x+cos‌2‌x=0 or cos‌2‌x−sin‌2‌x=0 ⇒‌‌tan‌2‌x=−‌