多元函数微分学,第11题怎么做?
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11. e^(2yz) + x + y^2 + z = 7/4, x = y = 1/2 时,得 z = 0.
两边对 x 求偏导,得 2ye^(2yz)∂z/∂x + 1 + ∂z/∂x = 0,
则 ∂z/∂x = -1/[1+2ye^(2yz)];
两边对 x 求偏导,得 2(z+y∂z/∂y)e^(2yz) + 2y + ∂z/∂y = 0,
则 ∂z/∂y = -2[y+ze^(2yz)]/[1+2ye^(2yz)].
x = y = 1/2 ,z = 0 时,∂z/∂x = -1/2, ∂z/∂y = -1/2,
dz = -(1/2)(dx+dy)
两边对 x 求偏导,得 2ye^(2yz)∂z/∂x + 1 + ∂z/∂x = 0,
则 ∂z/∂x = -1/[1+2ye^(2yz)];
两边对 x 求偏导,得 2(z+y∂z/∂y)e^(2yz) + 2y + ∂z/∂y = 0,
则 ∂z/∂y = -2[y+ze^(2yz)]/[1+2ye^(2yz)].
x = y = 1/2 ,z = 0 时,∂z/∂x = -1/2, ∂z/∂y = -1/2,
dz = -(1/2)(dx+dy)
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