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

Question

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

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Orla Orla 6 years 2020-10-15T05:12:37+00:00 2 Answers 147 views 0

Answers ( )

  1. Acacia
    0
    2020-10-15T05:13:54+00:00
    Reply

    `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`

  2. giahuy
    0
    2020-10-15T05:13:57+00:00
    Reply

    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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