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中學數學: 100√x =1200+2x 請列詳細步驟

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發問:

100√x =1200+2x 更新: 100√x =1200+2x x=?

最佳解答:

100√x =1200+2x 1200+2x - 100√x = 0 2x - 100√x + 1200 = 0 x - 50√x + 600 = 0 (√x)^2 - 50√x + 600 = 0 (This is a quadratic equation) Factorize (√x - 30)(√x - 20) = 0 √x = 30 or √x = 20 x = 30^2 = 900 x = 20^2 = 400 x = 400 or 900 (answer) Check: 100√400 =1200+2(400) 100(20) =1200+800 2000 =2000 100√900 =1200+2(900) 100(30) =1200+1800 3000 =3000

其他解答:

Hint: square the both sides.