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Express $8^{2x+3}$ in the form $2^y$, stating $y$ in terms of $x$. - Edexcel - A-Level Maths Pure - Question 5 - 2013 - Paper 3

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Express-$8^{2x+3}$-in-the-form-$2^y$,-stating-$y$-in-terms-of-$x$.-Edexcel-A-Level Maths Pure-Question 5-2013-Paper 3.png

Express $8^{2x+3}$ in the form $2^y$, stating $y$ in terms of $x$.

Worked Solution & Example Answer:Express $8^{2x+3}$ in the form $2^y$, stating $y$ in terms of $x$. - Edexcel - A-Level Maths Pure - Question 5 - 2013 - Paper 3

Step 1

Step 1: Express 8 in terms of 2

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Answer

We know that 88 can be expressed as a power of 22: 8=238 = 2^3. Therefore, we can rewrite the expression as:

82x+3=(23)2x+38^{2x+3} = (2^3)^{2x+3}

Step 2

Step 2: Apply the Power of a Power Rule

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Answer

Using the power of a power rule, which states that (am)n=amn(a^m)^n = a^{m \cdot n}, we can rewrite the expression as:

(23)2x+3=23(2x+3)=26x+9(2^3)^{2x+3} = 2^{3(2x+3)} = 2^{6x + 9}

Step 3

Step 3: State y in terms of x

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Answer

From the expression 26x+92^{6x + 9}, we can identify that in the form of 2y2^y, we have:

y=6x+9y = 6x + 9

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