giải thích rõ giùng mình luôn nha 5^ x+1 = 125 5^2x-3 – 2.5^2 = 5^2 .3 (9x + 2 ) .3 =60 3x – 129 = 6^5 : 6^2 3x = 81

0 bình luận về “giải thích rõ giùng mình luôn nha 5^ x+1 = 125 5^2x-3 – 2.5^2 = 5^2 .3 (9x + 2 ) .3 =60 3x – 129 = 6^5 : 6^2 3x = 81”

1. a. 

   `5^(x + 1) = 125`

   `⇔5^(x + 1) = 5^3`

   `⇔x + 1 = 3`

   `⇔x = 2`

   b.

   `5^(2x – 3) – 2*5^2 = 5^2 * 3`

   `⇔5^(2x – 3) – 2*25 = 25*3`

   `⇔5^(2x – 3) = 25*3 + 2*25`

   `⇔5^(2x – 3) = 75 + 50`

   `⇔5^(2x – 3) = 125`

   `⇔5^(2x – 3) = 5^3`

   `⇔2x – 3 = 3`

   `⇔2x = 6`

   `⇔x = 3`

   c.

   `(9x + 2) * 3 = 60`

   `⇔9x + 2 = 60 : 3`

   `⇔9x + 2 = 20`

   `⇔9x = 20 – 2`

   `⇔9x = 18`

   `⇔x = 18/9`

   `⇔x = 2`

   d.

   `3x – 129 = 6^5 : 6^2`

   `⇔3x – 129 = 6^(5-2)`

   `⇔3x – 129 = 6^3`

   `⇔3x = 6^3 – 129`

   `⇔3x = 216 – 129`

   `⇔3x = 87`

   `⇔x = 29`

   e.

   `3x = 81`

   `⇔x = 81/3`

   `⇔x = 27`

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2. `5^{x+1}=125`

   `=>5^{x+1}=5^3`

   `<=>x+1=3`

   `<=>x=2`

   –

   `5^{2x-3}-2.5^2=5^2 .3`

   `=>5^{2x-3}=5^3`

   `<=>2x-3=3`

   `<=>2x=6`

   `<=>x=3`

   –

   `(9x+2).3=60`

   `=>9x+2=20`

   `<=>9x=18`

   `<=>x=2`

   –

   `3x-129=6^5:6^2`
   

   `=>3x-129=6^3`

   `<=>3x=345`

   `<=>x=115`

   –

   `3x=81`

   `=>x=81:3`

   `<=>x=27`

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