`cos^(2)(x-2y)=1-2(dy)/(dx),` where `x-2y=u`

sec^(2)(x-2y)(1-2(dy)/(dx))=1, where x-2y=u

(x-y+1)(dy)/(dx)=x-y+2 , where x-y=u

1-(dy)/(dx)=sec(x-y)," where "x-y=u

1+(dy)/(dx)=cos(x+y), where x+y=u

1+(dy)/(dx)=cos(x+y), where x+y=u

(x-y)(1-(dy)/(dx))=e^(y), where x-y=u A) ue^u-e^u=e^(x)+c B) u^(2)=e^(x)+c C) u^(2)=(1)/(2)e^(x)+c D) u^(2)e^(x)=2x+c

Using the substitution shown against them : cos (x-2y) + 2(dy)/(dx) = 0, x-2y = u

(x-y)^(2) (dy)/(dx) =a^(2), x -y =u

(x+y)(dx-dy)=dx+dy , where x+y=u

(dy)/(dx)=sin(x+y)+cos(x+y), where x+y=u