Determine the values of a and b that satisfy the equation. $$\sqrt { - 81 } - 7 = a + b i$$
A) $a = 14 ; b = 18$
B) $a = 49 ; b = - 9$
C) $a = 81 ; b = - 7$
D) $a = - 9 ; b = 7$
E) $a = - 7 ; b = 9$

Question

Quizplus · Accepted Answer

The square root of -81 is 9i (since $\sqrt{-81} = \sqrt{81} \cdot \sqrt{-1} = 9i$), and subtracting 7 gives $9i - 7$, which matches the form $a + bi$ with $a = -7$ and $b = 9$.

Determine the Values of a and B That Satisfy the Equation