It is given that 3^2X+1 = 5^2-X (I) find the exact value of 45X (Ii)find exact value of X, correct to 2sf?
回答 (1)
2016-04-15 3:46 pm
3^(2x+1) = 5^(2-x)
(2x+1) log(3) = (2-x) log(5)
(2x+1) / (2-x) = log(5)/log(3)
(2x+1) = (2-x) 1.46497
2x+1 = 2.92994 - 1.46497x
3.46497x = 1.92994
x = 1.92994 / 3.46497
x = 0.556986
45x = (0.556986)(45) = 25.06437
(2x+1) log(3) = (2-x) log(5)
(2x+1) / (2-x) = log(5)/log(3)
(2x+1) = (2-x) 1.46497
2x+1 = 2.92994 - 1.46497x
3.46497x = 1.92994
x = 1.92994 / 3.46497
x = 0.556986
45x = (0.556986)(45) = 25.06437
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https://hk.answers.yahoo.com/question/index?qid=20160415072904AAn90ZO