Algebra · real student question

Write the fraction 256/625 as a power.

Question

Write 256625\dfrac{256}{625} as a power.

Step-by-step solution

  1. Factor each part into a prime power first. Repeated division shows

    256=28,625=54256=2^{8},\qquad 625=5^{4}

    This already answers the question in one form, 2854\dfrac{2^{8}}{5^{4}}, but the exponents differ, so the fraction cannot yet be written as a single power.

  2. Look for a common exponent. Since 8=428=4\cdot 2, regroup the numerator as a fourth power:

    28=(22)4=442^{8}=\left(2^{2}\right)^{4}=4^{4}

    Now both numerator and denominator carry the same exponent 44: 256=44256=4^4 and 625=54625=5^4.

  3. Fold the equal exponents into one power of a fraction. The quotient rule for powers, anbn=(ab)n\dfrac{a^{n}}{b^{n}}=\left(\dfrac{a}{b}\right)^{n}, applies exactly when the exponents match:

    256625=4454=(45)4\frac{256}{625}=\frac{4^{4}}{5^{4}}=\left(\frac{4}{5}\right)^{4}

  4. Check the value. (45)4=44445555=256625\left(\dfrac{4}{5}\right)^{4}=\dfrac{4\cdot 4\cdot 4\cdot 4}{5\cdot 5\cdot 5\cdot 5}=\dfrac{256}{625}. ✓ Also note 256625\dfrac{256}{625} is already in lowest terms, since 22 and 55 share no factor — that is why no cancelling was possible.

  5. Know which form to hand in. (45)4\left(\dfrac{4}{5}\right)^{4} is the requested single power; 2854\dfrac{2^{8}}{5^{4}} is the prime-factored form. Both are correct, but only the first is one power of one base.

Answer

256625=(45)4=2854\frac{256}{625}=\left(\frac{4}{5}\right)^{4}=\frac{2^{8}}{5^{4}}

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