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Select the correct answer.

Write [tex]\sqrt{64} - \sqrt{-289}[/tex] as a complex number in the form of [tex]a + b i[/tex].

A. [tex]8 - 17i[/tex]

B. [tex]17 + 8i[/tex]

C. [tex]-17 - 8i[/tex]

D. [tex]8 + 17i[/tex]


Sagot :

To solve the problem of writing [tex]\(\sqrt{64} - \sqrt{-289}\)[/tex] as a complex number in the form of [tex]\(a + bi\)[/tex], follow these steps:

1. Calculate the square root of 64:
[tex]\[ \sqrt{64} = 8 \][/tex]
since [tex]\(8 \times 8 = 64\)[/tex].

2. Calculate the square root of -289:
The square root of a negative number introduces the imaginary unit [tex]\(i\)[/tex], where [tex]\(i = \sqrt{-1}\)[/tex]. So,
[tex]\[ \sqrt{-289} = \sqrt{289} \cdot i = 17i \][/tex]
because [tex]\(17 \times 17 = 289\)[/tex].

3. Combine the results:
Now, substitute the calculated values into the original expression [tex]\(\sqrt{64} - \sqrt{-289}\)[/tex]:
[tex]\[ \sqrt{64} - \sqrt{-289} = 8 - 17i \][/tex]

4. Express the result as a complex number:
The expression [tex]\(8 - 17i\)[/tex] is already in the form [tex]\(a + bi\)[/tex], where [tex]\(a = 8\)[/tex] and [tex]\(b = -17\)[/tex].

Thus, the expression [tex]\(\sqrt{64} - \sqrt{-289}\)[/tex] as a complex number in the form [tex]\(a + bi\)[/tex] is [tex]\(8 - 17i\)[/tex].

The correct answer is:
A. [tex]\(8 - 17i\)[/tex].