## Calculus 8th Edition

conjugate: $-1-2\sqrt{2}i$ modulus: 3
To find the conjugate of a complex number, we reverse the sign of the imaginary part, like so: $\overline{-1+2\sqrt{2}i}$ $=-1-2\sqrt{2}i$ We find the modulus using the formula $\sqrt{a^2+b^2}$ for $a+bi$: $|-1+2\sqrt{2}i|$ $=\sqrt{(-1)^{2}+(2\sqrt{2})^{2}}$ $=\sqrt{1+8}$ $=\sqrt{9}$ $=3$