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d(xy) = (x+dx) (y+dy) - xy. f ’ (x) = f(x 0 + h) – f(x 0 ). d(xy) = (x+dx) (y+dy) - xy d(xy) = xy + xdy + ydx + dxdy – xy. d(x) = xdy +ydx + dxdy. d(xy) = xdy + ydx. PRODUKTREGLEN!!111. Eksempel på brug af produktreglen:. y = 5 x 2. dy = 5 • (x + dx)(x + dx) - 5 x 2.
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d(xy) = (x+dx) (y+dy) - xy f’(x) = f(x0 + h) – f(x0) d(xy) = (x+dx) (y+dy) - xy d(xy) = xy + xdy + ydx + dxdy – xy d(x) = xdy +ydx + dxdy d(xy) = xdy + ydx PRODUKTREGLEN!!111
Eksempel på brug af produktreglen: y = 5x2 dy = 5 • (x + dx)(x + dx) - 5x2 dy = 5 • (x2 + 2xdx + (dx)2) - 5x2 dy = 5x2 + 10xdx + 5(dx)2 - 5x2 dy = 10xdx dy = 10x dx