Ta có: \(9\cdot5^{x-2}+7\cdot5^{x-1}-5^x=2375\)

\(\Leftrightarrow5^x\cdot\dfrac{9}{25}+5^x\cdot\dfrac{7}{5}-5^x\cdot1=2375\)

\(\Leftrightarrow5^x\cdot\dfrac{19}{25}=2375\)

\(\Leftrightarrow5^x=2375:\dfrac{19}{25}=2375\cdot\dfrac{25}{19}=3125\)

\(\Leftrightarrow5^x=5^5\)

hay x=5

Vậy: x=5

(5+6,5)x = 875-1-1

11,5x = 873

x = 873:11,5

x = \(\frac{1746}{23}\)

a) 2^{x - 1} + 2^{x + 1} = 20

=> 2^x : 2 + 2^x . 2 = 20

=> 2^x . 1/2 + 2^x . 2 = 20

=> 2^x.(1/2 + 2)        = 20

=> 2^x . 5/2               = 20

=> 2^x                        = 20 : 5/2

=> 2^x                         = 8

=> 2^x                          = 2³

=>   x                          = 3

Ta có kết quả:

= 875 + 1875 : 25 - 875

= 875 + 75 - 875

= 950 - 875

= 75

nha bn

Vậy ta có:

= (875 - 875) + (375 : 25 x 5)

= 0 + (375 : 25 x 5)

= 0 + (15 x 5)

= 0 + 75

= 75

nha bn

A, 32 * 47 + 32 * 53 

  = 32 * ( 47 + 53 )

  = 32 * 100

  = 3200 .

B, 875 + 5375 : 25 - 875

  = 875 - 875 + 5375 : 25

  = 0 + 2115

  = 215 .

C, 5 * 25 * 2 * 16 * 4

  = ( 5 * 2 * 16 ) * ( 25 * 4 )

  = 160 * 100

  = 16000 .

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