Course1_dls_week4: Building your deep neural network step by step_ where is dz being calculated?

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The linear backward function has dz as an argument , but can’t see it being calculated any where, just being used . Or has everything being done in the dnn_utils already?

Where is linear_backward called? It is from linear_activation_backward, right? I suggest you have another careful look through the instructions. Everything is explained there.