Giúp mình vế c,d 

it is said that teengers are under a lot of stress and pressure.write a paragrap (from 120-150 words) to suggest way to gets rid of these problem. 

Giải Phương trình: \(\sqrt{2x+5}-\sqrt{3x-5}=2\)

Chứng minh rằng:

a, sin⁴x - cos⁴x= 2 sin² x-1

b, \(\dfrac{1}{sin^2x}\) + \(\dfrac{1}{cos^2x}\) = tan²x + cot²x +2