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GCSE maths, SURDS (A/A*) "Work out the value of (√2+√8)^2."

hi, guys, i can't figure out the answer to this question. "Work out the value of (√2+√8)^2." I tried expanding.. didn't work. how on earth do I get the right answer... am I going about it wrong, do I need to simplify? what should I do?
Original post by WarHammer-
hi, guys, i can't figure out the answer to this question. "Work out the value of (√2+√8)^2." I tried expanding.. didn't work. how on earth do I get the right answer... am I going about it wrong, do I need to simplify? what should I do?


Have you tried simplifying the bracket? root 8 = ?
Reply 2
yes. 2√2. should I always try to simplify?
answer would be 18..
root 2 x root 2 = 2
root 2 x root 8 = root 16 (which equals 4... and then 4 x 2 since you have root 16 twice)
root 8 x root 8 = 8
2+(4x2)+8 = 18
Reply 4
oh yes, that makes sense. thank you. but should I always try to simplify any surds which are easy to do?
Original post by WarHammer-
hi, guys, i can't figure out the answer to this question. "Work out the value of (√2+√8)^2." I tried expanding.. didn't work. how on earth do I get the right answer... am I going about it wrong, do I need to simplify? what should I do?


(√2+√8)^2 can also be written as (√2+√8)(√2+√8) so when you multiply out the brackets √2 will be multipled by √8 and √2 and the same goes for √8.
You should know when 2 surds -that are the same- are multiplied it becomes a full number. So √8 multiplied by itself will give you 8 same goes for the √2, it becomes 2. Now you are left with √2*√8 and another √2*√8 they both will give seprate answers of √16 and root of 16 is 4.
Now you are left with 2+4+4+8

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