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PLEASE HELP A-level C2 maths logs homework

Can somebody please help me with this maths question, it is asking me to find the value of p but I'm unsure how to do that. any help would be welcome, with an explanation too if that is okay. Thank you :smile:
c2.jpg
Reply 1
Original post by Imo_rai
Can somebody please help me with this maths question, it is asking me to find the value of p but I'm unsure how to do that. any help would be welcome, with an explanation too if that is okay. Thank you :smile:
c2.jpg


If you have 2f(x)=2f(x)\displaystyle 2^{f(x)} = 2^{f(x)} then you can ascertain that g(x)=f(x)g(x) = f(x), but in this case, obviously both sides are not powers of 2. So you need to make them into that. Notice that 4=224 = 2^2, so you can write:

2p+1=4p2    2p+1=(22)p2    2p+1=22(p2)\displaystyle 2^{p+1} = 4^{p-2} \iff 2^{p+1} = \left(2^2\right)^{p-2} \iff 2^{p+1} = 2^{2(p-2)} and hence, we know that: p+1=2(p2)p+1 = 2(p-2) from which it should be easy to solve for pp.

For the second one, try and do it yourself, it's the same method, except we write 125=53125 = 5^3.
Original post by Imo_rai
Can somebody please help me with this maths question, it is asking me to find the value of p but I'm unsure how to do that. any help would be welcome, with an explanation too if that is okay. Thank you :smile:
c2.jpg


For part c) 4 is 2 squared. Is that a clue? Can you rearrange the rhs now?

Look for something similar in d)
Reply 3
Original post by Zacken
If you have 2f(x)=2f(x)\displaystyle 2^{f(x)} = 2^{f(x)} then you can ascertain that g(x)=f(x)g(x) = f(x), but in this case, obviously both sides are not powers of 2. So you need to make them into that. Notice that 4=224 = 2^2, so you can write:

2p+1=4p2    2p+1=(22)p2    2p+1=22(p2)\displaystyle 2^{p+1} = 4^{p-2} \iff 2^{p+1} = \left(2^2\right)^{p-2} \iff 2^{p+1} = 2^{2(p-2)} and hence, we know that: p+1=2(p2)p+1 = 2(p-2) from which it should be easy to solve for pp.

For the second one, try and do it yourself, it's the same method, except we write 125=53125 = 5^3.


thank you so much for your help, I can do it now :smile:
Reply 4
Original post by maggiehodgson
For part c) 4 is 2 squared. Is that a clue? Can you rearrange the rhs now?

Look for something similar in d)


Thank you, I understand it now :smile:
Reply 5
Original post by Imo_rai
thank you so much for your help, I can do it now :smile:


Welcome. :smile:

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