Question

Work out the value of y in:

3(4 y + 2)  ÷  9(y - 2) = 1/27

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Answer

The exponential equation can be written as:

3 (4 y + 2)  =    

 9 (y - 2)          27


Step 1: Express everything with base 3

We know:

9 = 32

27 = 33


NB - 1/27 becomes 3 - 3


So rewrite:

3 (4 y + 2)   =  3 - 3

(3 2) y - 2


Step 2: Apply exponent rules

(32) y-2 = 3 2(y -2)  = 3 2y - 4 

Now the equation becomes:

3 4y + 2 = 3 -3

3 2y - 4


Step 3: Use the quotient rule for exponents

3 4y + 2 

3 2y - 4

= 3 (4y + 2) - (2y - 4) 

= 3 (4y + 2 - 2y + 4)

= 3 2y + 6


3 2y + 6 = 3  - 3


Step 4: Equating exponents (since bases are the same)

2y + 6 = −3

2y = −9


y = − 9/2

Final Answer:

y = − 9/2

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