1. Question: `(x^a/x^b)^(a + b) xx (x^b/x^c)^(b + c) xx (x^c/x^a)^((1)/(ca)) = ?`

    A
    0

    B
    `x^1/(abc)`

    C
    `x^1/(ab + bc + ca)`

    D
    `1`

    Note: Given Exp.`x^((a - b)/(ab)) . x^((b - c)/(ab)) . x^((c - a)/(ca))` `= x^(a^2 - b^2) + (b^2 - c^2) + (c^2 - a^2)` `= x^0 = 1.`
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  2. Question: `(x^a/x^b)^(1/(ab)) xx (x^b/x^c)^(1/(bc)) xx (x^c/x^a)^(1/(ca)) = ?`

    A
    1

    B
    `x^1/(abc)`

    C
    `x^1/(ab + bc + ca)`

    D
    None

    Note: Not available
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  3. Question: If` (a/b)^(x - 1) = (b/a)^(x - 3)` then x is equal is :

    A
    1

    B
    `1/2`

    C
    `2`

    D
    `7/2`

    Note: `(a/b)^(x - 1) = (b/a)^(x - 3) <=> (a/b)^(x - 1) = (a/b)^(3 - x)` `:. x - 1 = 3 - x or 2x = 4 or x = 2`
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  4. Question: If` 2^x xx 8^(1/5) = 2^(1/5)` then x is equal to :

    A
    `1/5`

    B
    `- 1/2`

    C
    `2/5`

    D
    ` - 2/5`

    Note: `2^x xx 8^(1/5) <=> (2^x xx 2^(3/5))/(2^(1/5)` `= 1 <=> 2^x xx 2(3/5 - 1/5) = 1` `or 2(x + 2/5) = 2^0.` So,` x + 2/5 = 0 or x = - 2/5`
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  5. Question: If` sqrt(5) + 3sqrt(x) = 3,` then x is equal to :

    A
    125

    B
    64

    C
    27

    D
    9

    Note: On squaring both sides, we get : `5 + sqrt(x) = 9 or 3sqrt(x) = 4` Cubing both sides, we get `x = (4 xx 4 xx 4) = 64`
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  6. Question: If` 5^(x + 3) = (25)^(3x - 4),` then the value of x is :

    A
    `5/11`

    B
    `11/5`

    C
    `11/3`

    D
    `13/5`

    Note: `5^(x + 3) = (25)^(3x - 4 ) `or 5^(x + 5) = 5^(2(3x - 4) or 5^(x + 5)` `= 5^(6x - 8)` `:. x + 3 = 6x - 8 or 5x = 11 or x = 11/5.`
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  7. Question: If` 3sqrt(32) = 2^x`, then x is equal to :

    A
    5

    B
    3

    C
    `3/5`

    D
    `5/3`

    Note: `3sqrt(32) = 2^x => (2^5)^(1/5)` `= 2^x => 2^x = 2^(5/3)` `:. x = 5/3`
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  8. Question: If` a^x = b^y = c^z` and` b^2 = ac,` then y equals :

    A
    `(xz)/(x + z)`

    B
    `(xz)/(2(x - z))`

    C
    `(xz)/(2(z - x))`

    D
    `(2xz)/(x + z)`

    Note: Let` a^2 = b^y = c^z = k` Then `a = k^(1/x), b = k^(1/y)` and `c = k^(1/z)` `b^2 = ac => k^(2/y)` ` = k^(1/z) => k^(2/y) = k^(1/x + 1/z)` `:. 2/y = 1/x + 1/z or 2/y` `= (x + z)/(xz) or y = (2xz)/(x + z)`
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  9. Question: If` 2^x = 3^y = 6^-z,` then` (1/x + 1/y + 1/z)` is eequal to :

    A
    0

    B
    1

    C
    `3/2`

    D
    `- 1/2`

    Note: `2^x = 3^y = 6^-z` `= k => 2 = k^(1/x), 3 = k^(1/y) & 6 = k^(- 1/z)` Now `2 xx 3 = 6 => k^(1/x) xx k^(1/y)` `= k^(- 1/2) => k(1/x + 1/y)` `= k^(- 1/z)` `:. 1/x + 1/y = - 1/z or 1/x + 1/y + 1/z = 1`
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  10. Question: If` x = y^a, y = z^b` and `z = x^c`, then the value of abc is :

    A
    4

    B
    3

    C
    2

    D
    1

    Note: `x = y^a = (z^b)^a` ` = z^ab = (x^c)^ab = x^(abc)` `:. abc = 1`
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