3. Consider a system of two second order ODEs: y" + al (x)y' + a2(x)y = f(x) 2" + b1 (ac) z' + 62(2) z = g(2) By introducing the variables u1 = y, u2 = y', u3 = z, and u4 = 2', show that this can be written as a first order system T' = A(x) U + F(x) , u(x) = U2 (x) U3 (x) where A(x) is an appropriately defined matrix valued function and F(x) is an appropriately defined vector valued function