Answer:
54
Step-by-step explanation:
![\frac{4}{3} \pi r^{3} =12\pi \\r=\sqrt[3]{9} \\surface area 4\pi r^{2} = 4\pi (\sqrt[3]{9} )^2=54.372 (3dp)](https://tex.z-dn.net/?f=%5Cfrac%7B4%7D%7B3%7D%20%5Cpi%20r%5E%7B3%7D%20%3D12%5Cpi%20%5C%5Cr%3D%5Csqrt%5B3%5D%7B9%7D%20%5C%5Csurface%20area%204%5Cpi%20r%5E%7B2%7D%20%3D%204%5Cpi%20%28%5Csqrt%5B3%5D%7B9%7D%20%29%5E2%3D54.372%20%283dp%29)
Answer:
x = -2 + 2 i or x = -2 - 2 i
Step-by-step explanation:
Solve for x:
x^2 + 4 x + 8 = 0
Subtract 8 from both sides:
x^2 + 4 x = -8
Add 4 to both sides:
x^2 + 4 x + 4 = -4
Write the left hand side as a square:
(x + 2)^2 = -4
Take the square root of both sides:
x + 2 = 2 i or x + 2 = -2 i
Subtract 2 from both sides:
x = -2 + 2 i or x + 2 = -2 i
Subtract 2 from both sides:
Answer: x = -2 + 2 i or x = -2 - 2 i
