MCQ
If (16)2x+3 = (64)x+3, then 42x-2 =
  • A
    64
  • B
    256
  • C
    32
  • D
    512

Answer

  1. 256
    Solution:
    We have to find the value of 42x-2 provided (16)2x+3 = (64)x+3
    So,
    (16)2x+3 = (64)x+3
    (24)2x+3 = (26)x+3
    28x+12 = 26x+18
    Equating the power of exponents we get
    8x +12 = 6x +18
    8x - 6x = 18 - 12
    2x = 6
    $\text{x}=\frac{6}{2}$
    x = 3
    The value of 42x-2 is
    = 42x-2
    = 42×3-2
    = 46-2
    = 44
    = 256
    Hence the correct alternative is b.

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