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C2 Logarithms - Help Needed :)

Hi all, I'm really stuck on this C2 problem concerning Logarithms as I dont even know how to approach it! Any help would be appreciated!

Part a) When coffee is made its temperature is 90 degrees. After t mins, the temperature of the coffee is given by:

90(0.88)^t degrees

Find after how many mins the temperature of the coffee is 45 degrees

Part b) Solve for x and y the simultaneous equations

log(base 2)x - log(base 2)y = 4
log(base 2)x^2 + log(base 2)y^3 = -7
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IgorYakov
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Original post by MatthewP01
Hi all, I'm really stuck on this C2 problem concerning Logarithms as I dont even know how to approach it! Any help would be appreciated!

Part a) When coffee is made its temperature is 90 degrees. After t mins, the temperature of the coffee is given by:

90(0.88)^t degrees

Find after how many mins the temperature of the coffee is 45 degrees

Part b) Solve for x and y the simultaneous equations

log(base 2)x - log(base 2)y = 4
log(base 2)x^2 + log(base 2)y^3 = -7



For part (a) You have 90×0.88t=45 90 \times 0.88^t = 45 can you think of a log rule that will make t the subject?

For part (b) can you think of a log rule that will enable you to combine the logs so you have log2(..)=4 log_2(..) = 4 and log2(...)=−7 log_2 (...) = -7 ?

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