Math Question (PreCalc)

[SlayerZ99]

So I have to simplify this expression. This is what I got. And my other question is when do you cross multiply and when you you multiply top -> top and bottom -> bottom? (Represented in the blue)



EDIT: another question. The (square root of 6) + 1 / square root of 5

[Ad Bot]

[Choi]

You don't cross when multiplying fractions like that, you only cross when they're separated by an equal sign

[SlayerZ99]

You don't cross when multiplying fractions like that, you only cross when they're separated by an equal sign

Oh ok. Because I did a lot of cross multiplying in Physics which got me confused.

[Swollow]

Oh ok. Because I did a lot of cross multiplying in Physics which got me confused.

you cross multiply when separated by an equal signs because you are actually multiplying the factors to the other side by there inverse, it's just faster to multiply across like so

[BluetoothBoy]

   _             _        __      _
(/6 + 1) / (/5) = (/30 + /5) / 5

[SlayerZ99]

  _             _        __      _
(/6 + 1) / (/5) = (/30 + /5) / 5

why divided by 5?
oh crap i cross multiplied again...

See I got just Square of 30 + Square of 5.

So how do you get divided by 5?

[Ipquarx]

why divided by 5?
oh crap i cross multiplied again...

See I got just Square of 30 + Square of 5.

So how do you get divided by 5?

You multiply by the denominator to remove the radical, so in this case (sqrt 5)² = 5.

[BluetoothBoy]

Well, I used my algebraic calculator, so I doubt it's wrong. I could do it without if you need to see it, I guess.

[SlayerZ99]

You multiply by the denominator to remove the radical, so in this case (sqrt 5)² = 5.

Multiply everything by the denominator?
So thats why you get the /30 + /5 on top too?

[Gumba Jonny]

yeah
the denominator can't be a radical
ever

[SlayerZ99]

swag
understand now
thanks guys <3

[Blockzillahead]

equal sign determines if you cross multiply or not


also is the last one
(√ 6)+(1/√ 5)
or
(√ 6+1)/√ 5
?

[BluetoothBoy]

To expand upon what Gumba said, it's generally a bad idea to have a radical in the denominator because it makes things like adding and subtracting fractions harder (since a radical in decimal form is lengthy and can be easily made an integer by squaring it).

equal sign determines if you cross multiply or not


also is the last one
(√ 6)+(1/√ 5)
or
(√ 6+1)/√ 5
?

The last one.

[Scriode]

http://wolframalpha.com

[Ipquarx]

http://wolframalpha.com

While I would normally consider this cheating, they do have a step-by-step option.