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Can u solve these 2 equations without calculator?

3.9^(x+1) = 27^(x-1)

2.4^(x+1) = 16^(2x)

^ means : to the power of.

5 Answers

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  • DOVE
    Lv 6
    9 years ago
    Favourite answer

    9^(x+1) = 27^(x-1)

    (3^2)^(x+1)= (3^3)^(x-1)

    3^2(x+1)= 3^3(x-1)

    2(x+1)=3(x-1)

    2x+2=3x-3

    x=5

    4^(x+1) = 16^(2x)

    (2^2)^(x+1)=(2^4)^(2x)

    2^2(x+1)= 2^(8x)

    2(x+1)=8x

    2x+2=8x

    6x=2

    x=1/3

  • Como
    Lv 7
    9 years ago

    This presentation is rather misleading.

    Will take a guess at :-

    Qu1

    3.9^(x + 1) = 27^(x - 1)

    3.3^(2x + 2) = 3^(3x - 1)

    3^(2x + 3) = 3^(3x - 1)

    2x + 3 = 3x - 1

    4 = x

    Qu 2

    2.4^(x+1) = 16^(2x)

    2 [ 2^(2x + 2) ] = 2^(8x)

    2^(2x + 3) = 2^(8x)

    2x + 3 = 8x

    3 = 6x

    x = 1/2

    Will have another guess as to how questions are meant to read:-

    Qu 1

    [ 9^(x + 1) ] = 27^(x - 1)

    [ 3^(2x + 2) ] = 3^(3x - 3)

    2x + 2 = 3x - 3

    5 = x

    Qu 2

    4^(x + 1) = 16^(2x)

    4^(x + 1) = 4^(4x)

    x + 1 = 4x

    1 = 3x

    x = 1/3

    PS

    Out of interest could you clarify how questions were meant to be read?

  • 9 years ago

    (3)9^(x+1) = 27^(x-1)

    or 3^2( x+1) = 3^3( x-1)

    or 2(x+ 1) = 3 ( x- 1 )

    or 2x + 2 = 3x -3

    or x= 5 ans

    proof ------------------------------------

    9^(5+1) = 9^6 = (3^2)^6 = 3^12

    27^(5-1) =27^4 = (3^3)4 = 3^12

    (2) 4^(x+1) = 16^(2x)

    or 4^(x+1) = 4^2*2x= 4^4x

    or x+ 1 = 4x

    or x= 1/3 ans

    proof-------------

    4^(1/3+ 1) =4^4/3

    16^( 2*1/3) = 4^2*2/3= 4^4/3

  • Anonymous
    9 years ago

    3.9^(x+1) = 27^(x-1) OR 3^(2x + 3) = 3^(3x -- 3) whence 3x -- 3 = 2x + 3 OR x = 6 ANSWER

    2.4^(x+1) = 16^(2x) OR 2^(2x + 3) = 2^(8x) whence 8x = 2x + 3 OR 6x = 3 OR x = 1/2 ANSWER

  • 9 years ago

    no

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