Root Question

[jasonmaehara]

Couldn't find this in any search so here it goes. Overall I'd say I'm okay with root however this problem seems to be giving me some trouble...

(√(9+√80) + √(9-√80))^2

Answer: 20

I know it's in the format of x^2+2xy+y^2 but I'm having trouble expanding the middle term.

[RonPurewal]

per our forum rules, please post the problem with all of its answer choices, and then we'll answer it. (this will help especially in this case, because, as you will see, there's a good backup method based on the answer choices.)

by the way, here's a square root sign that you can copy and paste in order to make the question more legible:
√

[jasonmaehara]

My apologies.

A) 1
B) 9 - 4√5
C) 18 - 4√5
D) 18
E) 20

OA: E

[tim]

as Ron mentioned, there is a great shortcut method for this problem. just estimate the answer and you'll see you can eliminate some wrong answers. as for helping you further though, i'd like to see what work you did on expanding and where you got hung up. i'd also like to see you copy the question correctly, because the question you have written does not have an answer of 20..

[krishnan.anju1987]

This question is wrong. The question is in the given link.

rt-9-rt80-rt-9-rt80-2-t345.html

[jnelson0612]

This question is wrong. The question is in the given link.

rt-9-rt80-rt-9-rt80-2-t345.html

Thank you for the correction! I will edit the problem.