7. (12 分) The usual way to evaluate the improper integraldx (from 0 to ∞) is first to calculate its square: dxdy (double integral from 0 to ∞ for both x and y). Evaluate the integral and solve the resulting equation for I.
(a) (8 分) Find the value of at the point (1, 1, 1) if the equation
xy + z³x - 2yz = 0
defines z as a function of the two independent variables x and y and the partial derivative exists.
50. CO2 雷射切割機是國教署教學設備清單重點項目,可精準切割、雕刻或畫記圖案,試問:假設實線為切割模式、虛線為掃描模式,則下列何者較符合圖八向量圖形加工後的效果?
(A) (B) (C) (D)