loglogloglog..........math高手please come_0－lgzrelv的部落格

標題:

loglogloglog..........math高手please come

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發問:

Q1)5^(x+1) + 5^x =2 4 Q2)(3^y) (4^y) = 48

最佳解答:

5^(x+1) + 5^x =2 4 5^x * 5^1+5^x=24 5^x (5+1)=24 5^x=4 x=0.8614// (3^y) (4^y) = 48 (3*4)^y=48 12^y=48 y=1.5579//

其他解答:

1. 5^(x+1) + 5^x =24 5(5^x)+ (5^x) =24 because 5 times5^x = 5^(X+1) 6(5^x) = 24 5^x = 4 both sides take log x log 5 = log4 x = log5/log4 2. (3^y) (4^y) = 48 (a^x) (b^x) = ab^x 12^y = 48 both sides take log x log 12 = log 48 x = log48/log12|||||A1) 5^(x+1) + 5^x =24 5(5^x)+ (5^x) =24 ........因為 5乘5^x = 5^(X+1) 6(5^x) = 24 5^x = 4 .................;2邊take log x log 5 = log4 x = log5/log4 A2) (3^y) (4^y) = 48 ..............;(a^x) (b^x) = ab^x 12^y = 48 ............. ;２邊take log x log 12 = log 48 x = log48/log12|||||1. 5^(x+1) + 5^x =24 5^x ．5+5^x=24 5^x(5+1)=24 5^x=4 x= log (5) 4 2. (3^y) (4^y) = 48 (3+4)^y=48 12^y=48 y= log (12) 48