rational manipulation

Ryan$

Full Member
Joined
Jan 25, 2019
Messages
291
Hi guys, I just want to verify about something:
why it's right that if I want to calculate x over this equation:

a:b
x:c

then to calculate x, I do (a*c)/b , why it's right? it makes no sense for me, any clue why that rule is always right?!
 

Romsek

Full Member
Joined
Nov 16, 2013
Messages
336
\(\displaystyle \dfrac a b = \dfrac x c \)

multiply both sides by \(\displaystyle c\)

\(\displaystyle \dfrac{a c}{b} = \dfrac{c x}{c} = x\)
 
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