Add or subtract.
-$( 7 + \sqrt { - 2 } ) + ( 5 - \sqrt { - 72 } )$
A) $12 - 5 \mathrm { i } \sqrt { 2 }$
B) $12 + 5 \sqrt { 2 }$
C) $12 - 5 \sqrt { 2 }$
D) $12 + 5 \mathrm { i } \sqrt { 2 }$

Question

Quizplus · Accepted Answer

To solve this, combine like terms and simplify the square roots of negative numbers using $i$ (where $i = \sqrt{-1}$). $\sqrt{-2} = i\sqrt{2}$ and $\sqrt{-72} = \sqrt{36 \cdot 2} \cdot i = 6i\sqrt{2}$. So, $ ( 7 + i\sqrt{2} ) + ( 5 - 6i\sqrt{2} ) = 12 - 5i\sqrt{2}$.

Add or Subtract (7+−2)+(5−−72)( 7 + \sqrt { - 2 } ) + ( 5 - \sqrt { - 72 } )(7+−2​)+(5−−72​)

Add or Subtract $( 7 + \sqrt { - 2 } ) + ( 5 - \sqrt { - 72 } )$