Question

@jdoe0001

Answer 1

Do you know what to change the sqrt-9 to ? :)

Answer 2

\(\bf 5+\sqrt{-9}\qquad {\color{brown}{ \sqrt{-9}\to \sqrt{-1\cdot 9}\to \sqrt{-1\cdot 3^2}\to \sqrt{-1}\sqrt{3^2} }}\qquad thus
\\ \quad \\
5+\sqrt{-9}\implies 5+\sqrt{-1}\sqrt{3^2}\implies ?\)

Answer 3

8

Answer 4

\(5+\sqrt{-9}\qquad {\color{brown}{ \sqrt{-9}\to \sqrt{-1\cdot 9}\to \sqrt{-1\cdot 3^2}\to \sqrt{-1}\sqrt{3^2} }}\qquad thus
\\ \quad \\
5+\sqrt{-9}\implies 5+\sqrt{-1}\sqrt{3^2}\implies 5+\sqrt{-1}\cdot 3\implies 5+i\cdot 3
\\ \quad \\
5+3\cdot i\implies 5+3i\)

Answer 5

Think of what's in the sqrt sign as the 9 being multiplied by a negative 1.
First just take the sqrt of 9. And the sqrt of -1 is the imaginary number :)

Answer 6

Thank you both!