Q. \( [(-\tfrac{1}{2})^{-3}\cdot(-\tfrac{1}{2})^{-1}]^2=[(-\tfrac{1}{2})^{-4}]^2=(-\tfrac{1}{2})^{-8}\).
Answer
\( [(-\tfrac{1}{2})^{-3}\cdot(-\tfrac{1}{2})^{-1}]^2=[(-\tfrac{1}{2})^{-4}]^2=(-\tfrac{1}{2})^{-8}\).
\((- \tfrac{1}{2})^{-8}:(- \tfrac{1}{2})^{-3}=(-\tfrac{1}{2})^{-5},\) and \( (-\tfrac{1}{2})^{-5}=-32,\) so \(-32+32=0.\)
Final result: \(0\)
Detailed Explanation
We simplify the expression step by step:
\( [(-\frac{1}{2})^{-3} \cdot (-\frac{1}{2})^{-1}]^2 : (-\frac{1}{2})^{-3} – (-\frac{1}{2})^{-5} = [(-\frac{1}{2})^{-4}]^2 : (-\frac{1}{2})^{-3} – (-32) = (-\frac{1}{2})^{-8} : (-\frac{1}{2})^{-3} + 32 = (-\frac{1}{2})^{-5} + 32 = -32 + 32 = 0.\)
The original expression is:
\(\left[\left(-\frac{1}{2}\right)^{-3}\cdot\left(-\frac{1}{2}\right)^{-1}\right]^2:\left(-\frac{1}{2}\right)^{-3}-\left(-\frac{1}{2}\right)^{-5}\)
- Simplify the product inside the brackets using the rule \(a^m\cdot a^n=a^{m+n}\).\(\left(-\frac{1}{2}\right)^{-3}\cdot\left(-\frac{1}{2}\right)^{-1}=\left(-\frac{1}{2}\right)^{-3+(-1)}\)\(\left(-\frac{1}{2}\right)^{-3+(-1)}=\left(-\frac{1}{2}\right)^{-4}\)
- Raise the result to the second power using the rule \((a^m)^n=a^{mn}\).\(\left[\left(-\frac{1}{2}\right)^{-4}\right]^2=\left(-\frac{1}{2}\right)^{-4\cdot2}\)\(\left(-\frac{1}{2}\right)^{-4\cdot2}=\left(-\frac{1}{2}\right)^{-8}\)
- Divide by \(\left(-\frac{1}{2}\right)^{-3}\) using the rule \(\frac{a^m}{a^n}=a^{m-n}\).\(\left(-\frac{1}{2}\right)^{-8}:\left(-\frac{1}{2}\right)^{-3}=\left(-\frac{1}{2}\right)^{-8-(-3)}\)\(\left(-\frac{1}{2}\right)^{-8-(-3)}=\left(-\frac{1}{2}\right)^{-5}\)
- Now subtract the last term of the original expression.\(\left(-\frac{1}{2}\right)^{-5}-\left(-\frac{1}{2}\right)^{-5}=0\)
- A quick numerical check confirms the result.\(\left(-\frac{1}{2}\right)^{-5}=(-2)^5=-32\)\(-32-(-32)=0\)
Final answer: \(0\)
See full solution
Arithmetic FAQs
How do you multiply powers with the same base, e.g. \(\left(-\frac{1}{2}\right)^{-3}\cdot\left(-\frac{1}{2}\right)^{-1}\)?
Use \(a^{m}a^{n}=a^{m+n}\). So \(\left(-\frac{1}{2}\right)^{-3}\cdot\left(-\frac{1}{2}\right)^{-1}=\left(-\frac{1}{2}\right)^{-4}\,.\)
How do you apply a power to a power, e.g. \(\left(-\frac{1}{2}\right)^{-4}\)^{2}?
Use \( (a^{m})^{n}=a^{mn} \). So \(\left(-\frac{1}{2}\right)^{-4}\right)^{2}=\left(-\frac{1}{2}\right)^{-8}\)..
How do you divide powers with the same base, e.g. \(\left(-\frac{1}{2}\right)^{-8} : \left(-\frac{1}{2}\right)^{-3}\)?
Use \(a^{m}\div a^{n}=a^{m-n}\). Thus \(\left(-\frac{1}{2}\right)^{-8}\div\left(-\frac{1}{2}\right)^{-3}=\left(-\frac{1}{2}\right)^{-5}\,.\)
How do you evaluate a negative exponent, e.g. \(\left(-\frac{1}{2}\right)^{-5}\)?
\(a^{-n}=\left(\tfrac{1}{a}\right)^{n}\) or flip base: \(\left(-\tfrac{1}{2}\right)^{-5}=\left(-2\right)^{5}=-32\). Negative exponent means reciprocal; sign follows parity of exponent..
Why does subtracting a negative become addition, e.g. \(-\left(-\frac{1}{2}\right)^{-5}\)?.
Because \(a-(-b)=a+b\). So \(-(-\frac{1}{2})^{-5} = +(-\frac{1}{2})^{-5}\); with values, \(-(-32)=+32\)..
How does parity of the exponent affect sign, e.g. \( \left(-\frac{1}{2}\right)^{n} \)?
How does parity of the exponent affect sign, e.g. \( \left(-\frac{1}{2}\right)^{n} \)?
Why can you simplify stepwise instead of computing decimals immediately?
Laws of exponents keep expressions exact and simpler: combine exponents, then evaluate integer powers. This avoids rounding and reveals cancellations like \(-32+32=0\)..
Could a similar expression ever be undefined or infinite?
Only if you try exponent \(0\) in the denominator, like dividing by \(0\) or base \(0\) with negative exponent. Here base \(-\tfrac{1}{2}\) is nonzero, so all negative exponents are well-defined.
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