Rational equations intro | Algebra 2 | Khan Academy

When we have an equation where the variable is in the denominator of a quotient, that's a rational equation. We can solve it by multiplying both sides by the denominator, but we have to look out for extraneous solutions in the process.

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[TheFolkRevival]

Why not just do:
3(x+1) = 2(9-x)
3x+3 = 18-2x
5x = 15
x = 3

Was there a reason for doing it in this way?

[notsosecretaccount]

you can get to x=3 faster if you cross-multiply, it just a tip

[IllogicalFallacy]

2:23, why and when do you know whether you should use the reciprocal, apart from the term being a faction?