| Exam Board | OCR |
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| Module | Further Additional Pure (Further Additional Pure) |
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| Session | Specimen |
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| Topic | Second order differential equations |
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3 Given \(z = x \sin y + y \cos x\), show that \(\frac { \partial ^ { 2 } z } { \partial x ^ { 2 } } + \frac { \partial ^ { 2 } z } { \partial y ^ { 2 } } + z = 0\).