Toán Lớp 7: 2^x+1=64.16/2^8
3^3x+3^3x+2=7290
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Toán Lớp 7: 2^x+1=64.16/2^8
3^3x+3^3x+2=7290
Comments ( 2 )
Giải đáp:
Lời giải và giải thích chi tiết:
2^x+1=64.16/2^8
⇔2^x+1 =4
⇔2^x+1=2^2
⇔x+1=2
⇔x=1
3^3x+3^3x+2=7290
3^3x+3^3x.3²=7290
3^3x(1+3²) =7290
3^3x.10 =7290
3^3x =7290:10
3^3x =729
3^3x =3^6
⇔ 3x=6
x=6:3
x=2
a, 2^(x+1) = 64. 16/(2^8)
=> 2^(x+1) = 64. (2^4)/(2^8)
=> 2^(x+1) = 64. 1/(2^4)
=> 2^(x+1) = 64. 1/16 = 4
=> 2^(x+1) = 2^2
=>x+1 = 2
=> x = 2-1
=> x = 1
Vậy x = 1
b, 3^(3x) + 3^(3x+2) = 7290
=> 3^(3x) + 3^(3x). 3^2 = 7290
=> 3^(3x). (1+3^2) = 7290
=> 3^(3x). 10 = 7290
=> 3^(3x) = 7290 : 10
=> 3^(3x) = 729
=> 3^(3x) = 3^6
=> 3x = 6
=> x = 2
Vậy x = 2