Question

Solve for number eight

Answer 1

So factor -27
-27=-1 times 3 times 3 times 3
∛(-1 times 3 times 3 times 3)=3 times ∛-1
remember that ∛-1=-1
2 times ∛-1=3 times -1=-3
now we have
5 times (-3)+18
5 times -3=-15
-15+18=3
answer is 3

Answer 2

You cannot have a negetive number inside a cube root. So we use an "i" instead.

This is how you do it:
$5 \sqrt[3]{-27} + 18$                   $\sqrt[3]{-27}$ becomes $3i$
$5(3i) + 18$                       multiply
$15i + 18$                         reduce
$3(5i + 6)$