f.5 解方程 (20點) EMERGENT

👨🏻‍🏫 學術台數學

匿名

2011-10-28 2:40 am

請教我做圈住咗嗰3題

圖片參考：http://imgcld.yimg.com/8/n/HA00230702/o/701110270056713873486050.jpg

更新1:

按右鍵「另存圖片」再開啟睇會清楚d 答案 : 7. 9,9/16 11. 90,131.8,228.2,270 14. 117649,1/49

回答 (1)

myisland8132

2011-10-28 3:49 am

✔ 最佳答案

7 Ley y = √x4x + 9 = 15√x4y^2 - 15y + 9 = 0y = 3/4 or y = 3X = 9/16 or x = 911 Let y = cosθ3y^2 + 2y = 0y = 0 or y = -2/3So cosθ = 0 or cosθ = -2/3θ = 90,131.8,228.2,27014 Let y = log_7xy^2 - 4y - 12 = 0(y - 6)(y + 2) = 0y = -2 or y = 6log_7 x = -2 or log_7 x = 6logx/log7 = -2 or logx/log7 = 6logx = log(7^-2) or logx = log(7^6)x = 1/49 or 117649

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