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9 (a) Express $$\sqrt{10^{100} \times 10^{100}}$$ as a power of 10 (b) Liam was asked to express $(12^y)$ as a power of 12 Liam wrote $(12^y) = 12^2 = 12^{2y}$ - Edexcel - GCSE Maths - Question 10 - 2022 - Paper 3

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9-(a)-Express--$$\sqrt{10^{100}-\times-10^{100}}$$-as-a-power-of-10---(b)-Liam-was-asked-to-express-$(12^y)$-as-a-power-of-12-Liam-wrote-$(12^y)-=-12^2-=-12^{2y}$-Edexcel-GCSE Maths-Question 10-2022-Paper 3.png

9 (a) Express $$\sqrt{10^{100} \times 10^{100}}$$ as a power of 10 (b) Liam was asked to express $(12^y)$ as a power of 12 Liam wrote $(12^y) = 12^2 = 12^{2y}$. L... show full transcript

Worked Solution & Example Answer:9 (a) Express $$\sqrt{10^{100} \times 10^{100}}$$ as a power of 10 (b) Liam was asked to express $(12^y)$ as a power of 12 Liam wrote $(12^y) = 12^2 = 12^{2y}$ - Edexcel - GCSE Maths - Question 10 - 2022 - Paper 3

Step 1

Express $$\sqrt{10^{100} \times 10^{100}}$$ as a power of 10

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Answer

To express 10100×10100\sqrt{10^{100} \times 10^{100}} as a power of 10, we first apply the property of square roots: a×b=a×b\sqrt{a \times b} = \sqrt{a} \times \sqrt{b}. Hence,

10100×10100=10100×10100\sqrt{10^{100} \times 10^{100}} = \sqrt{10^{100}} \times \sqrt{10^{100}}

Now, using the property of square roots that states 10n=10n2\sqrt{10^n} = 10^{\frac{n}{2}}, we can write:

10100=101002=1050\sqrt{10^{100}} = 10^{\frac{100}{2}} = 10^{50}

Thus,

10100×10100=1050×1050\sqrt{10^{100} \times 10^{100}} = 10^{50} \times 10^{50}

Finally, applying the property of exponents that states am×an=am+na^m \times a^n = a^{m+n}, we have:

1050×1050=1050+50=1010010^{50} \times 10^{50} = 10^{50 + 50} = 10^{100}.

Step 2

Explain why Liam's method is wrong.

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Answer

Liam's method is incorrect because he misapplied the exponent rule for expressions with powers. The correct approach to express 12y12^y requires recognizing that:

12y12^y should remain as 12y12^y, not equal to 12212^2. Instead, we should retain the expression as is. The proper way to handle the exponent is to write:

(12y)=12y(12^y) = 12^{y}.

In Liam's case, because he incorrectly placed a power inside and outside the bracket, he multiplied the exponent erroneously by 2, failing to recognize that:

(12y)122(12^y) \neq 12^2

Therefore, Liam should have represented it accurately to retain its definition rather than relying on unverified transformations.

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