Write the complex conjugate of the complex number. Then multiply the number by its complex conjugate. $\sqrt { - 25 }$
A) $- i , 25$
B) $- 5 i , 25$
C) $5 i , 25$
D) $625 i , 25$
E) $- 24 i , 25$

Question

Write the complex conjugate of the complex number. Then multiply the number by its complex conjugate. $\sqrt { - 25 }$ 
A) $- i , 25$
B) $- 5 i , 25$
C) $5 i , 25$
D) $625 i , 25$
E) $- 24 i , 25$

Quizplus · Accepted Answer

The complex number is $\sqrt{-25} = 5i$. The complex conjugate of $5i$ is $-5i$. Multiplying $5i$ by its complex conjugate $-5i$ gives $5i \times -5i = -25i^2$. Since $i^2 = -1$, this simplifies to $25$.

Write the Complex Conjugate of the Complex Number −25\sqrt { - 25 }−25​

Write the Complex Conjugate of the Complex Number $\sqrt { - 25 }$