Question

Jika 2^x -3.2^1-x -5 =0 maka...
A.1
B.-1
C.6
D. 2log6
E. 6log2

Answer 1

2^x - 3 .2^(1 - x) - 5 = 0  ..... kalikan engan 2^x

(2^x)² - 3 . 2 - 5 .2^x = 0
     (2^x)² - 5. 2^x - 6 = 0
    (2^x - 6) (2^x + 1) = 0
    2^x - 6 = 0       atau   2^x  + 1 = 0
         2^x = 6       atau         2^x  = - 1  (tak memenuhi)
   log 2^x = log 6       
  x . log 2 = log 6
            x = (log 6) / (log 2)
            x = ² log 6