For the functions w = - 7x + 5y , x = cost, and y = sint, express dw dt as a function of t, both by using the chain rule and by expressing w in terms of t and differentiating directly with respect to t. Then evaluate dw dt at t = - dw Express dt as a function of t. dw dt dw Evaluate dt at t= - dw dt (Type an exact answer, using radicals as needed.)ow ow For the functions w = xy + yz + xz, x = 2u + 3v, y= 2u -3v, and z = uv, express ow ow du and - using the chain rule and by expressing w directly in terms of u and v before differentiating. Then evaluate du av and - at the point (u,v) = 2, -4 aw aw Express au and as functions of u and v. dw = du aw av ow ow Evaluate au and av at 3 1 - 4. ow (Type an integer or a simplified fraction.) ow av ( 3 - 4 ) = 0 (Type an integer or a simplified fraction.)