函数\(z = \ln \left( {3x + {y^4}} \right)\)的全微分为
A: \(dz = { { 3 + {y^4}} \over {3x + {y^4}}}dx + { { 3x + 4{y^3}} \over {3x + {y^4}}}dy\)
B: \(dz = {3 \over {3x + {y^4}}}dx + { { 4{y^3}} \over {3x + {y^4}}}dy\)
C: \(dz = {3 \over {3x + {y^4}}}dy + { { 4{y^3}} \over {3x + {y^4}}}dx\)
D: \(dz = {3 \over {3x + {y^4}}}dx - { { 4{y^3}} \over {3x + {y^4}}}dy\)
A: \(dz = { { 3 + {y^4}} \over {3x + {y^4}}}dx + { { 3x + 4{y^3}} \over {3x + {y^4}}}dy\)
B: \(dz = {3 \over {3x + {y^4}}}dx + { { 4{y^3}} \over {3x + {y^4}}}dy\)
C: \(dz = {3 \over {3x + {y^4}}}dy + { { 4{y^3}} \over {3x + {y^4}}}dx\)
D: \(dz = {3 \over {3x + {y^4}}}dx - { { 4{y^3}} \over {3x + {y^4}}}dy\)
举一反三
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