Answer:
7. Option D
9. Option B
10. Option C
Step-by-step explanation:
According to Vieta's Formulas, if

are solutions of a given quadratic equation:
Then:
is the completely factored form of

.
If choose

, then:

So, according to Vieta's formula, we can get:

But

:
Their least common multiple is 12.
No, it is an imaginary number.
Can't take the square root of a negative number without creating a method termed an imaginary number, which is the square root of -1 which they have used " i " to signify.
Then square root of -11.2 would be written Sqrt(11.2)i. The Sqrt(11.2) = 3.3466
so the answer is 3.3466i
The square root of 400 is 20