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指數&對數問題
發問:
Q1 : 5^(x+1) + 5^x =24 Q2 : 3^x X 4^x = 48 更新: 答案:q1=0.86 q2=1.56 更新 2: 5^(x+1) + 5^x =24 5(5^x)+5^x=24 點解5^(x+1) = 5(5^x) = 25^x 問:(5^1=5) + (5^x) =25^x???
最佳解答:
Q1 : 5^(x+1) + 5^x =24 5(5^x)+5^x=24 6(5^x)=24 5^x=4 log 5^x=log 4 x log 5=log 4 x=log 4 / log 5 = 0.86 (correct to 2 sign. fig.) Q2 : 3^x X 4^x = 48 log (3^x X 4^x) = log 48 log 3^x + log 4^x = log 48 x log 3 + x log 4 = log 48 x (log 3 + log 4) = log 48 x log (3 X 4) = log 48 x log 12 = log 48 x = log 48 / log 12 = 1.56 (correct to 2 sign. fig.) 希望幫到你
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