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Special Types Of First_Order Equations Part_1

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Special Types Of First_Order Equations  Part_1 : Standard Form 1 :                 Equations involving only p and q ,The equations of this form are                 f(p,q) = 0 .......(1) Charpit's equations take the forms     dx/[∂f/∂p] = dy/[∂f/∂q]=dz/[p∂f/∂p+q∂f/∂q]                      = dp/0 = dq/0 ∴       dp = 0 ⇒p = constant = a (say) .......(2) Substituting in equation(1) , we get                 f(a,q) = 0 ......(3) which gives q = φ(a) = constant  Hence dz = pdx + qdy                    = a dx + φ(a) dy  Which on integration yields            z = ax + φ(a)y + c .......(4) Example _ 1 : ...