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# surds question proof Watch

1. show that( √75-√12)/(√75+√12) simplifies to 3/7
how the f do you do this?
2. (Original post by p29)
show that( √75-√12)/(√75+√12) simplifies to 3/7
how the f do you do this?
you multiply by ( √75-√12)/(√75-√12)*
3. (Original post by p29)
show that( √75-√12)/(√75+√12) simplifies to 3/7how the f do you do this?
its rationalising i think
4. (Original post by p29)
show that( √75-√12)/(√75+√12) simplifies to 3/7
how the f do you do this?
Nice one. It doesn't simplify to 3/7. Try again.
5. (Original post by the bear)
you multiply by ( √75-√12)/(√75-√12)*
that gives me 27
what do i do next??
6. (Original post by RDKGames)
Nice one. It doesn't simplify to 3/7. Try again.
oh f*** off
7. (Original post by RDKGames)
Nice one. It doesn't simplify to 3/7. Try again.
ermm you are wrong

*
8. (Original post by p29)
that gives me 27
what do i do next??
the numerator ( top bit ) goes to 27

the denominator ( bottom bit ) goes to 63 *
9. (Original post by the bear)
ermm you are wrong

*
Oh lol there's a slash in there. I legit missed that. People should really start using latex.
10. (Original post by the bear)
the numerator ( top bit ) goes to 27

the denominator ( bottom bit ) goes to 63 *
thank you
11. (Original post by p29)
show that( √75-√12)/(√75+√12) simplifies to 3/7
how the f do you do this?

12. Multiply the fraction by the denominator's conjugate surd over the same conjugate to rationalise and simplify.

EDIT: The conjugate surd method only works for some surds. Not all rationalising factors need be the same as the conjugate surd. All the surds I'm imagining you're going to work with will work by using the conjugate surd.
13. (Original post by AlexLawrence1453)
Full solution...
Let's not post full solutions to problems.
14. (Original post by AlexLawrence1453)
Multiply the fraction by the denominator's conjugate surd over the same conjugate to rationalise and simplify.

EDIT: The conjugate surd method only works for some surds. Not all rationalising factors need be the same as the conjugate surd. All the surds I'm imagining you're going to work with will work by using the conjugate surd.
thank you
15. (Original post by p29)
thank you
There's been quite a lot of overcomplication in this thread!

Note that

and

.

I'll leave you to do the cancellation

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