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# multiplying surds watch

1. (2root5 + 3 root 6) ^2

how do you multiply this and can you tell me how you got to each stage
2. If it's ^2, then the two brackets are the same, so it's (2√5 + 3√6) (2√5 + 3√6).

Then you do the FOIL method or the beak method or whatever you call it (basically first outer inner last)

If you multiply two of the same thing together like 2√5 x 2√5, then it's 2 x 2 and then √5 x √5, multiplied together, which is 20.

You should be able to work it out from that.
3. (Original post by esmeralda123)
(2root5 + 3 root 6) ^2

how do you multiply this and can you tell me how you got to each stage
Expand it as you would a quadratic (distribution rules), for example, ie.

(a+b)^2 --> (a+b)(a+b) --> a(a+b) + b(a+b) --> a^2 + 2ab + b^2, with a being 2rt5, and b being 3rt6.
4. (Original post by Fractite)
If it's ^2, then the two brackets are the same, so it's (2√5 + 3√6) (2√5 + 3√6).

Then you do the FOIL method or the beak method or whatever you call it (basically first outer inner last)

If you multiply two of the same thing together like 2√5 x 2√5, then it's 2 x 2 and then √5 x √5, multiplied together, which is 20.

You should be able to work it out from that.
why is root 5 x root 5 20, i thought it was 5
5. (Original post by esmeralda123)
(2root5 + 3 root 6) ^2

how do you multiply this and can you tell me how you got to each stage
https://youtu.be/07bqa_rEtuU?t=2m19s
6. (Original post by esmeralda123)
(2root5 + 3 root 6) ^2

how do you multiply this and can you tell me how you got to each stage
(2root5 + 3 root 6) ^2
= (2root5 + 3root6)*(2root5 + 3root6)

FOIL- First, Outers, Inners, Last

= (2root5*2root5) + (2root5*3root6) + (3root6*2root5) + (3root6+3root6)
= 4root25 + 6root30 + 6root30 + 9root36
= 4*5 + 6root30 + 6root30 + 9*6
= 20 + 12root30 + 54
= 74 + 12root30

I think that's right anyway...
7. (Original post by esmeralda123)
why is root 5 x root 5 20, i thought it was 5
It is 5, I multiplied it by the 2x2, which is 4.

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