We can rewrite some differential equations by substitution to ones which we can solve. (a) Use the substitution v = 2 x + 7y+1 to rewrite the following differential equation dy (2x + 7y+1)- = cos(x) dx 2 ²7/7 dv in the form of = f(x, v). dx Enter the expression in x and v which defines the function f in the box below. (2x + 7y+1) For example, if the DE can be rewritten as dv = 4 v e5x, enter 4*v*exp(5*x) dx dy dx Y (b) Use the substitution v = to rewrite the following differential equation X + cos 2y+7x X dv in the form of = g(x, v). dx Enter the expression in x and v which defines the function g in the box below.

i need some help with this ordinary differential equations question, please provide full working out and final answer. thank you!

Need only handwritten solution only (not typed one).