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derived demand (衍生需求) is the demand for factors of production (生產的因素...kind of raw materials ) to build house. The demand for cement is derived from the demand for housing, but the cement itself. So, cement ...

In proving the equation, it is assumed that the primary and secondary coil have no resistance. As such, the voltage applied to the primary is counter-balanced by the back emf. Apply Faraday's Law to the primary coil...

(a) dy/dx = -1/( 2√(2)x^(3/2) ) (b) f'(x) = (1/3)x^(-2/3) = 1/( 3x^(2/3) )

Your first question is not clear. The equation of the curve cannot be read. 2009-12-12 00:16:19 補充： (2)(a) y = 4x^2 - 2x - 1 dy/dx = 8x - 2 Gradient at (1,1) is 8 - 2 = 6 (b) dy/dx = 0 => x = 1/4 d^2y/dx^2 = 8 => min Minimum of y = 4*(1/4)^2 - 2(1/4) - 1...

45.2a (5) v = t^2 - t m/s a(t) = dv/dt = 2t - 1 m/s^2 a(3) = 2(3) - 1 = 5 m/s^2 when a(t) = 0, 2t - 1 = 0 t = 1/2 s 45.4 (2) Let the radius and height be r and h m respectively Volume = πr^2h = 100 h = 100/πr^2 Total surface area S = πr^2 (base) + 2πrh (wall) = πr^2 + 2πr(100/πr^2) = πr^2 + 200/r...

1. The charge Q at (0,a) will give a potnetial at point (x,0) given by V(x) = k.Q/sqrt(a^2+x^2) where k is a constant(=9x10^9 N.m^2/C^2) [sqrt stands for square-root] By symmetry, the charge at (0,-a) also gives the same potnetial at (x,0) thus the total...

(1)F[spring] = -ky ,where y is the displacement and positive k is known as the stiffness.(Hooke's law) (2)F[friction] = -by' ,where positive b is the damping coefficient negative signs in equations (1) and (2) reflect the opposite nature of the...

生產更多傢俱, 不錯是需要更多木材。但我們亦要明白, 在木材這項需求上, 是否可以增加供應? 增加供應當然第一需要木材這原材料是有足夠供應, 但我們知道, 過去的日子, 因着人對木材的需求增加, 已然令到一些本來是森林的地方的樹木全被砍伐, 熱帶雨林的面積己經大幅減少, 所以供應...