Question

Bài 1:      

 5^x+1-5^x=100

Bài 2:

9^2x:9=729

Answer 1

5^x+1 - 5^x = 100

5^x. 5 - 5^x . 1 = 100

5^x . ( 5 - 1 ) = 100

5^x . 4 = 100

5^x =100 : 4

5^x = 25

5^x= 5²

=> x = 2

2)

9^2x : 9 = 729

9^2x : 9¹ = 729

9^2x-1 = 729

9^2x-1 = 9³

=> 2x - 1 = 3

2x = 3 + 1

2x = 4

=> x = 4 : 2

x = 2

Answer 2

MÌNH LÀM CÂU 2 THÔI NHÉ

                                  9^2X:9=729

                                     9^2X=729:9

                                      9^2X=81

                                       9^2X=9²

              SUY RA;         2.X=2

                                       X=2:2

                                       X=1

Vậy x=1

Answer 3

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