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Mathematics 21 Online
OpenStudy (anonymous):

uniqueness Property

OpenStudy (anonymous):

OpenStudy (anonymous):

@precal do you by any chance know anything about uniqueness property

OpenStudy (anonymous):

in simple english what they want you to do is write both sides with the same base that is all lets work through this one step by step

OpenStudy (anonymous):

ok

OpenStudy (anonymous):

\[625^{2-a}=5^{2}\] is the start right?

OpenStudy (anonymous):

yep

OpenStudy (anonymous):

the base on the right is \(5\) and the base on the left is \(625\)

OpenStudy (anonymous):

now it turns out that \[5^4=625\]

OpenStudy (anonymous):

so we can rewrite the left hand side of \[625^{2-x}=5^2\] as \[\large (5^4)^{2-x}=5^2\]

OpenStudy (anonymous):

clear so far or no?

OpenStudy (anonymous):

yes

OpenStudy (anonymous):

k now we use the law of exponents on the left, that says when you raise to a power you multiply the exponents rewrite \[\large (5^4)^{2-x}=5^2\] as \[\large 5^{8-4x}=5^2\]

OpenStudy (anonymous):

note the use of the distributive law here since \[4(2-x)=8-4x\]

OpenStudy (anonymous):

so why does the 2 turn into a four istead of it being a -8 all together

OpenStudy (anonymous):

oh

OpenStudy (anonymous):

i jumped the gun but i hope i answered that question before you asked it is it clear now?

OpenStudy (anonymous):

yes

OpenStudy (anonymous):

ok now come the famous "uniqueness property"

OpenStudy (anonymous):

since \[\large 5^{8-4x}=5^2\] that means that \[8-4x=2\]

OpenStudy (anonymous):

and you can solve that equation for \(x\) in two steps, which is only elementary algebra, has nothing to do with exponents

OpenStudy (anonymous):

k

OpenStudy (anonymous):

you want to try another one from that paper, or no?

OpenStudy (anonymous):

yes please

OpenStudy (anonymous):

\[36^x=216\] looks tricky but it is not hard

OpenStudy (anonymous):

especially if you recognize \[36=6^2\]and \[216=6^3\]

OpenStudy (anonymous):

oh actually they used a \(b\) no matter \[36^b=216\\ 6^{2b}=6^3\] then by "uniqueness"\[2b=3\]

OpenStudy (anonymous):

k

OpenStudy (anonymous):

that is all good luck nice picture btw who drew it?

OpenStudy (anonymous):

some person on google lol could you help me with one more please

OpenStudy (anonymous):

OpenStudy (anonymous):

I just need help with this last problem

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