Answer:
x=πn, n∈Z
Step-by-step explanation:
if sin²2x=1-cos²2x, then
1-cos²2x-2cos2x+2=0; ⇒ cos²2x+2cos2x-3=0; ⇔ (cos2x+3)(cos2x-1)=0;
I missed the part where that's my problem
-7
you can use power rule of derivatives for that.
y = -49
multiply 7 on both sides
-7*7 = y/7*7
-49 = y