急!F5 more equations 1exq8－lgzrelv的部落格

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急!F5 more equations 1exq8

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請詳細步驟教我計以下二條 :(不要網址回答)1. tan x=(2+cos x)/3sin x . (where 0度<= x <360度)2. Mr Wong is a poultry stall owner. He bought a number of chickens for $1000 and sold each of them at a price of $18 more than its cost. A day before the start of the rest day for the poultry outlets. Mr Wong slaughtered all... 顯示更多請詳細步驟教我計以下二條 : (不要網址回答) 1. tan x=(2+cos x)/3sin x . (where 0度<= x <360度) 2. Mr Wong is a poultry stall owner. He bought a number of chickens for $1000 and sold each of them at a price of $18 more than its cost. A day before the start of the rest day for the poultry outlets. Mr Wong slaughtered all the 5 unsold live chickens and sold each of them at a price of $10 less than its cost. If Mr Wong made a total profit of $220. how many chickens did he buy ?

最佳解答:

1. tan x = (2 + cos x) / (3 sin x) 3 sin x tan x = 2 + cos x 3 sin2 x / cosx = 2 + cos x 3 (1 - cos2 x) = 2cos x + cos2 x 4cos2 x + 2cos x - 3 = 0 cos x = [ - 2 ± √ (22 - 4(4)(- 3)) ] / [2(4)] cos x = ( - 2 + √52 ) / 8 or ( - 2 - √52 ) / 8 (rejected) x = 49.35° or x = 310.65° (3 sig fig) 2. Let he bought u chickens = 1000/u.The price of chickens = (u-5)(1000/u + 18) The price of 5 unsold live chickens = (5)(1000/u - 10) (u - 5)(1000/u + 18) + (5)(1000/u - 10)= 220+1000 (1000+18u-5000/u-90)+(5000/u-50)=1220 18u=360 u= 20He bought 20 chickens.

其他解答:

1) tan x = (2 + cos x) / (3 sin x) 3 sin x tan x = 2 + cos x 3 sin2 x / cosx = 2 + cos x 3 (1 - cos2 x) = 2cos x + cos2 x 4cos2 x + 2cos x - 3 = 0 cos x = [ - 2 ± √ (22 - 4(4)(- 3)) ] / [2(4)] cos x = ( - 2 + √52 ) / 8 or ( - 2 - √52 ) / 8 (rejected since cos x ≥ - 1) x = 49.35368° or x = 310.64632° 2)Let he bought x chickens , then the cost of each = 1000/x.The price of x - 5 chickens = 1000/x + 18 The price of 5 unsold live chickens = 1000/x - 10 (x - 5)(1000/x + 18) + (5)(1000/x - 10) - 1000 = 220 (x - 5 + 5)(1000/x) + (x - 5)18 - 50 = 1220 1000 + (x - 5)18 - 50 = 1220 (x - 5)18 = 270 x = 20He bought 20 chickens.