標題:
S.2數學題 幫幫手~!!
發問:
9^(x+2)=36 求3^x = 請幫幫手...thanks!!
最佳解答:
9^(x+2)=36 3^2(x+2) = 36 3^(2x+4) = 36 3^2x * 3^4 = 36 3^2x = 36 / (3^4) (3^x)^2 = 4/9 3^x = √(4/9) 3^x = 2/3 2009-03-28 15:43:32 補充： 方法二 : 9^(x+2)=36 [3^(x+2)] ^ 2 = 6^2 (由於3^(x+2)不會是負數,下一步等式兩邊取正數) 3^(x+2) = 6 3^x * 3^2 = 6 3^x = 2/3
其他解答:
9^(x+2)=36 9^x+18=36 9^x=36-18 9^x=18 9^x/3=18/3 3^x=6|||||9x+18=36 9x=36-18 9x=18 x=2 3^(2)=6
S.2數學題 幫幫手~!!
發問:
9^(x+2)=36 求3^x = 請幫幫手...thanks!!
最佳解答:
9^(x+2)=36 3^2(x+2) = 36 3^(2x+4) = 36 3^2x * 3^4 = 36 3^2x = 36 / (3^4) (3^x)^2 = 4/9 3^x = √(4/9) 3^x = 2/3 2009-03-28 15:43:32 補充： 方法二 : 9^(x+2)=36 [3^(x+2)] ^ 2 = 6^2 (由於3^(x+2)不會是負數,下一步等式兩邊取正數) 3^(x+2) = 6 3^x * 3^2 = 6 3^x = 2/3
其他解答:
9^(x+2)=36 9^x+18=36 9^x=36-18 9^x=18 9^x/3=18/3 3^x=6|||||9x+18=36 9x=36-18 9x=18 x=2 3^(2)=6
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