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Maths AS June 2015 C1 pp (edexcel)

one of the questions says that, given that 2^x=y
express 4^x in terms of y
in the ms it says that the answer is y^2 but I don't understand how to get there
can someone help please?
Reply 1
Original post by ria1099
one of the questions says that, given that 2^x=y
express 4^x in terms of y
in the ms it says that the answer is y^2 but I don't understand how to get there
can someone help please?


You know that 4 = 2^2
So 4^x can be written as (2^2)^x
So then you just multiply out the powers to get 2^2x
Which is the same as (2^x)^2, so if y=2^x, 4^x = y^2
Reply 2
Original post by KaylaB
You know that 4 = 2^2
So 4^x can be written as (2^2)^x
So then you just multiply out the powers to get 2^2x
Which is the same as (2^x)^2, so if y=2^x, 4^x = y^2


ahh thank you, I completely forgot about doing it that way!!
Reply 3
Original post by ria1099
ahh thank you, I completely forgot about doing it that way!!


No problem :hat2:

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