Simplify sqaure root of 84

a. 7* square root of 12
b. 4* square root of 21
c. 21* square root of 2
d. 2* square root of 21

Question

Simplify sqaure root of 84

a. 7* square root of 12
b. 4* square root of 21
c.  21* square root of 2
d. 2* square root of 21

anonymous · Answer

|dw:1340937409925:dw|

Firstly tell me what are the factors of 84??

anonymous · Answer

another way could be just to use a calculator, since you already have the options. 

sqrt(84) = 9.16515139

7 * square root(12) = 24.2487113<--- so not this one right? try the rest. .. 
4 * square root(21) = 
21 * square root(2) = 
2 * square root(21) =

anonymous · Answer

She does not have a calculator..

anonymous · Answer

she has the internet, and google. google is one big calculator :)

anonymous · Answer

$$84 = 2*2*3*7$$

Take what you can take out of the square root brackets, and check the answer with the choices given..