Question

Which of the following is equivalent to

Answer 1

Answer:

Option (2) is correct.

$18-\sqrt{-25}=18-5i$

Step-by-step explanation:

Given expression $18-\sqrt{-25}$

We have to find an equivalence value to the expression.

Radical rule,

$\sqrt{-a}=\sqrt{-1} \sqrt{a}$

Also,$i=\sqrt{-1}$

Consider the given expression,

$18-\sqrt{-25}$

Applying radical rule to $\sqrt{-25}$

$\sqrt{-25}=\sqrt{-1}\sqrt{25}=5i$

Thus, the expression becomes,

$18-\sqrt{-25}=18-5i$

Thus, option (2) is correct.

Answer 2

Answer:

Choice B is correct.

Step-by-step explanation:

Given expression is

18-√-25

We have to simplify it.

As we know that

√-a=√-1.√a

Since we know that √-1=i

Hence,√-a=√ai

we can simplify given expression by using above equation.

18-√-25

18-√-1√25

18-i√25

18-√25i

As 25 is square of 5.

Hence ,

18-5i which is the answer.