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Find the exact value of $x$ for which $$ ext{log}_2(2x) = ext{log}_2(5x + 4) - 3$$ Given that $$ ext{log}_b(y) + 3 ext{log}_2(2) = 5$$ express $y$ in terms of $a$ - Edexcel - A-Level Maths Pure - Question 8 - 2013 - Paper 4

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Find-the-exact-value-of-$x$-for-which--$$-ext{log}_2(2x)-=--ext{log}_2(5x-+-4)---3$$--Given-that--$$-ext{log}_b(y)-+-3-ext{log}_2(2)-=-5$$--express-$y$-in-terms-of-$a$-Edexcel-A-Level Maths Pure-Question 8-2013-Paper 4.png

Find the exact value of $x$ for which $$ ext{log}_2(2x) = ext{log}_2(5x + 4) - 3$$ Given that $$ ext{log}_b(y) + 3 ext{log}_2(2) = 5$$ express $y$ in terms of $... show full transcript

Worked Solution & Example Answer:Find the exact value of $x$ for which $$ ext{log}_2(2x) = ext{log}_2(5x + 4) - 3$$ Given that $$ ext{log}_b(y) + 3 ext{log}_2(2) = 5$$ express $y$ in terms of $a$ - Edexcel - A-Level Maths Pure - Question 8 - 2013 - Paper 4

Step 1

Find the exact value of $x$ for which log_2(2x) = log_2(5x + 4) - 3

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Answer

To solve for xx, start by isolating the logarithmic terms:

  1. Rewrite the equation: extlog2(2x)+3=extlog2(5x+4) ext{log}_2(2x) + 3 = ext{log}_2(5x + 4)

  2. Use the property of logarithms that allows you to combine them: extlog2(2x)+extlog2(8)=extlog2(5x+4) ext{log}_2(2x) + ext{log}_2(8) = ext{log}_2(5x + 4)

  3. Apply the addition property of logarithms: extlog2(16x)=extlog2(5x+4) ext{log}_2(16x) = ext{log}_2(5x + 4)

  4. Set the arguments equal to each other: 16x=5x+416x = 5x + 4

  5. Rearrange to solve for xx: 16x5x=416x - 5x = 4 11x=411x = 4 x = rac{4}{11}

Step 2

Given that log_b(y) + 3log_2(2) = 5 express y in terms of a

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Answer

Start by isolating yy:

  1. Rewrite the equation using properties of logarithms: extlogb(y)=53extlog2(2) ext{log}_b(y) = 5 - 3 ext{log}_2(2)

  2. Simplifying gives: extlogb(y)=53 ext{log}_b(y) = 5 - 3 (since log2(2)=1log_2(2) = 1) extlogb(y)=2 ext{log}_b(y) = 2

  3. Convert the logarithmic equation to exponential form: y=b2y = b^2

  4. If we express bb in terms of aa, we get: y=a2y = a^2

Thus, yy is expressed in terms of aa as: y=a2y = a^2

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