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F.4 MATHS(more about equation)
發問:
solve the following equations1)2(4^x)-17(2^x)+8=02)2(logx base4 x)^2-7logx base4 -4=03)x-3√x-54=04)√(x+4)-√(2x-6)=15)The members of the science club plan to have a trip.The total expenses is $9000,which is to be shared equally among the members.however,three of them withdraw just before the trip,and each of... 顯示更多 solve the following equations 1)2(4^x)-17(2^x)+8=0 2)2(logx base4 x)^2-7logx base4 -4=0 3)x-3√x-54=0 4)√(x+4)-√(2x-6)=1 5)The members of the science club plan to have a trip.The total expenses is $9000,which is to be shared equally among the members.however,three of them withdraw just before the trip,and each of other members has to pay $150 more.how many members are there in the science club? 更新: ans as much as u can plz!!
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其他解答:
F.4 MATHS(more about equation)
發問:
solve the following equations1)2(4^x)-17(2^x)+8=02)2(logx base4 x)^2-7logx base4 -4=03)x-3√x-54=04)√(x+4)-√(2x-6)=15)The members of the science club plan to have a trip.The total expenses is $9000,which is to be shared equally among the members.however,three of them withdraw just before the trip,and each of... 顯示更多 solve the following equations 1)2(4^x)-17(2^x)+8=0 2)2(logx base4 x)^2-7logx base4 -4=0 3)x-3√x-54=0 4)√(x+4)-√(2x-6)=1 5)The members of the science club plan to have a trip.The total expenses is $9000,which is to be shared equally among the members.however,three of them withdraw just before the trip,and each of other members has to pay $150 more.how many members are there in the science club? 更新: ans as much as u can plz!!
最佳解答:
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1. 2(4^x) - 17(2^x) + 8 = 0 2(2^x)^2 - 17(2^x) + 8 = 0 let y = 2^x, 2y^2 - 17y + 8 = 0 (2y - 1)(y - 8) = 0 y = 1/2 , or y = 8 so, 2^x = 1/2 , or 2^x = 8 x log2 = - log2 , or x log2 = 3 log2 so, x = -1 , or x = 3 2. 你題目好似打多左個x , 我幫你改番做 2( logx base4 )^2 - 7( logx base4 ) - 4 = 0 let y = logx base4, 2y^2 - 7y - 4 = 0 (2y + 1)(y - 4) = 0 y = -1/2 , or y = 4 so, logx base4 = -1/2 , or logx base4 = 4 x = 4^(-1/2) , or x = 4^4 x = 1/2 , or x = 256 3. x - 3√x - 54=0 (√x)^2 - 3√x - 54 = 0 let y = √x , y^2 - 3y - 54 = 0 (y - 9)(y + 6) = 0 y = 9 or y = -6 so, x = 9^2 = 81 , or x = (-6)^2 = 36 (rejected) 4. √(x+4) - √(2x-6) = 1 [√(x+4) - √(2x-6) ] ^2 = 1^2 (x+4) - 2 [√(x+4)] [√(2x-6)] + (2x-6) = 1 3x - 3 = 2 [√ (2x^2 + 2x - 24) ] [ 3(x - 1) ] ^2 = (2^2) [√ (2x^2 + 2x - 24) ]^2 9(x^2 - 2x + 1) = 4(2x^2 + 2x - 24) x^2 - 26x + 105 = 0 (x - 21)(x - 5) = 0 x = 21 (rejected) , or x = 5 第5題食完飯再打 :) 希望幫到你:) 2011-08-24 14:10:55 補充： 5. Let there are x members (9000/x) (3) = (x - 3) (150) x^2 - 3x - 180 = 0 (x - 15)(x + 12) = 0 x = 15 , or x = -12 (rejected) so, there are 15 members in the science club x = -12 要rejected 因為人數唔會有負數 最多打300字,解釋唔到,希望幫到你 :) 2011-08-24 14:12:45 補充： 條式係因為失去的$=每人貼的$其他解答:
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