# Precalc

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how do you find x in 7-=log(x/10^-12)

• Precalc -

I will assume that -= is a typo and should be just =

7 = log(x/10^-12)
7 = logx - log 10^-12
7 = logx - (-12)
7-12= logx
-5 = logx
x = 10^-5

• Precalc -

the thing is its / instead of - so I thought that I multiply each side by 10^-12 but im not sure

• Precalc -

you cannot multiply by 10^12 because that is inside the log.

suppose you had 2 = √(x/4)
You can't multiply by 4, giving
8 = √x
because that would be trying to slide a value through the "walls" of the function calculation

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