Question

What is 2sin (2x+y) cos (x-2y)??

Answer 1

SOLUTION 1 : Begin with x3 + y3 = 4 . Differentiate both sides of the equation, getting

D ( x3 + y3 ) = D ( 4 ) ,

D ( x3 ) + D ( y3 ) = D ( 4 ) ,

(Remember to use the chain rule on D ( y3 ) .)

3x2 + 3y2 y' = 0 ,

so that (Now solve for y' .)

3y2 y' = - 3x2 ,

and

Answer 2

2.sin(2x+y).cos (x-2y)
=sin (2x+y+x-2y) [sin(A+B)+sin(A-B) = 2 sinA cosB ]
=sin (3x-y)

HOPE IT HELPS!!