Question

Write this expression as a complex number in standard form, a + bi.
(-3√-81)(-5+ √-9) + 9i

Answer 1

Answer:

81 + 144i

Step-by-step explanation:

Original equation

$(-3\sqrt{-81})(-5+\sqrt-9) + 9i$

Rewrite the radicals

$(-3\sqrt{81} * \sqrt{-1})(-5+\sqrt{9} * \sqrt{-1}) + 9i$

Simplify the radicals

$(-3 * 9i)(-5+3i) + 9i$

Simplify further

$(-27i)(-5+3i) + 9i$

Distribute the -27i

$135i - 81i^2 + 9i$

Add like terms

$- 81i^2 + 144i$

Square the i

$- 81 * (-1) + 144i$

Simplify

$81 + 144i$