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Student Support Forum > General > > "How to calculate the partial derivative?"

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Please answer this:2+7 =



Original Message (ID '144580') By yehuda:
Try this one It is base on leaving L1 and L2 as symbols, but defined as non constants, so derivatives according to x will not return 0 and the derivative of multiplication will be carried then replace only the terms of the derivatives l1 = a1 + b1*x + c1*y; l2 = a2 + b2*x + c2*y; l3 = a3 + b3*x + c3*y; D[L1 L2, x, NonConstants -> {L1 , L2}] /. {D[L1, x, NonConstants -> {L1, L2}] -> D[l1, x], D[L2, x, NonConstants -> {L1, L2}] -> D[l2, x]} This will also work with expressions such as D[L1^2 Sin[ L2^3], x, NonConstants -> {L1 , L2}] /. {D[L1, x, NonConstants -> {L1, L2}] -> D[l1, x], D[L2, x, NonConstants -> {L1, L2}] -> D[l2, x]} Try it yehuda