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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 6: a / 3 mũ x : 9 = 27 b/ 7 . 7 mũ x+ 1 = 343 c/ 5 mũ 5-y : 5 = 25 d/ 3 mũ y- 2 . 3 mũ y+ 2 = 81 e/ 7 mũ 5 -x = 343 Help me !

Toán Lớp 6: a / 3 mũ x : 9 = 27
b/ 7 . 7 mũ x+ 1 = 343
c/ 5 mũ 5-y : 5 = 25
d/ 3 mũ y- 2 . 3 mũ y+ 2 = 81
e/ 7 mũ 5 -x = 343
Help me !

Comments ( 2 )

  1. Hình ảnh .                

    toan-lop-6-a-3-mu-9-27-b-7-7-mu-1-343-c-5-mu-5-y-5-25-d-3-mu-y-2-3-mu-y-2-81-e-7-mu-5-343-help-m

  2. a, 3^{x} : 9 = 27
    ⇒ 3^{x} = 27 . 9 = 243
    ⇒ 3^{x} = 3^{5}
    ⇒ x = 5
    b, 7 . 7^{x + 1} = 343
    ⇒ 7 .  7^{x} . 7 = 343
    ⇒ 7 ^{x} = 343 : 7  : 7 = 7
    ⇒ x = 1
    c,5^{5 – y} : 5 = 25
    ⇒5^{5} : 5^{y} = 25 . 5= 125
    ⇒3125 : 5^{y} = 125
    ⇒5^{y} = 3125 : 125 = 25
    ⇒ y = 2
    d, 3^{y-2}. 3^{y+2} = 81
    ⇒ 3^{y} : 3^{2} . 3^{y} . 3^{2} = 81
    ⇒ 3^{(y – 2 ) + ( y + 2 )} = 3^{4}
    ⇒ 3^{2y}  = 3^{4}
    ⇒ 2y = 4
    ⇒ y = 2
    e,7^{5-x} = 343
    ⇒ 7^{5} : 7^{x} = 7^{3}
    ⇒ 7^{x} = 7^{5} : 7^{3} = 7^{2}
    ⇒ x = 2

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222-9+11+12:2*14+14 = ? ( )