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Mathematics 7 Online
OpenStudy (waheguru):

2^x = 64

OpenStudy (waheguru):

\[1/2^-x = 64/1\]

OpenStudy (asnaseer):

ok, so for questions like this, it often helps if you can reduce the equation down to something like:\[a^x=a^y\]because then you can immediately deduce that x=y

OpenStudy (asnaseer):

so here you are given:\[2^x=64\]so you need to see if you can express 64 as a power of 2

OpenStudy (waheguru):

as a power of 2?

OpenStudy (waheguru):

How do you know that

OpenStudy (asnaseer):

yes, because you have a power of 2 on the left-hand-side

OpenStudy (waheguru):

isnt the power x because the equation is 2^x

OpenStudy (asnaseer):

it is 2 to the power of x

OpenStudy (asnaseer):

so it is a "power of 2" expression

OpenStudy (waheguru):

arright

OpenStudy (asnaseer):

so, for 64, start with 2 and keep multiplying by 2 until you get to 64

OpenStudy (asnaseer):

with practice you will learn to recognise some well known powers of 2

OpenStudy (waheguru):

8?2 is 64 but how do I show that while soilveing it

OpenStudy (waheguru):

8^2*

OpenStudy (asnaseer):

start with 2, so:\[2^1=2\\ 2^2=2*2^1=4\\ 2^3=2*2^2=8\]etc

OpenStudy (waheguru):

Our teacher looks for proper form while solving, so how do I show my work while solving the equation, just by looking at it i can easily tell it was 8 but I dont understand how to properly show my work to find x

OpenStudy (asnaseer):

I understand - all you need to show is how you got 64 by multiplying 2's together - as I started showing you above. then you can proceed to solve the question given to you. and remember, we are looking for a power of 2 and not a power of 8

OpenStudy (asnaseer):

you could work backwards as well by taking square roots at each step as follows: \[2^x =64\]\[=(8)^2\]\[=((4)^2)^2\]etc

OpenStudy (asnaseer):

until you get to 2 inside the brackets

OpenStudy (asnaseer):

e.g. suppose you had to solve:\[3^x=27\]we could do it like this:\[3^x=81\]\[=(9)^2\]\[=((3)^2)^2\]\[=3^4\]therefore:\[x=4\]

OpenStudy (asnaseer):

*I meant 81 on the first line up there

OpenStudy (asnaseer):

not 27

OpenStudy (asnaseer):

that is an example of the "backwards" solution I was talking about

OpenStudy (asnaseer):

alternatively, you could solve it as follows:\[3^1=3\]\[3^2=3*3^1=9\]\[3^3=3*3^2=27\]\[3^4=3*3^3=81\]therefore:\[81=3^4\]therefore, if:\[3^x=81\]then:\[3^x=3^4\]therefore:\[x=4\]

OpenStudy (waheguru):

x = 6 for this problem

OpenStudy (asnaseer):

correct :)

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