Question

Which expression is equal to 2 sqrt -28

4 sqrt7i
-4 sqrt7
-4i sqrt7
4i sqrt 7

Answer 1

Which expression is equal to
`2√(-28)`

Solution

Step 1:

We have to rewrite
`√(-28)` =
`√(-1) √(28)`

`2√(-1) √(28) \\`

Step 2:

`√(-1)  = i\\`

Now plug in the above value in the step 1, we get

`2i√(28)`

We can write
`√(28) = √(4) √(7) = 2√(7)`

Step 3:

Now, we plug in
`√(28) = 2√(7)` in the above expression , we get

`2i*2*√(7) \\`

Step 4:

Simplifying, we get

`4i√(7)`

Therefore, the answer is d) 4i sqrt 7