Answer
$\frac{-2\pm\sqrt {2}}{2}$.
Work Step by Step
Step 1. Use the given coefficients of the polynomial to set up a division as shown in the figure.
Step 2. Perform a synthetic division and find the quotient as $4x^2+8x+2$.
Step 3. Solve $4x^2+8x+2=0$ to get $x=\frac{-8\pm\sqrt {8^2-4(4)(2)}}{2(4)}=\frac{-2\pm\sqrt {2}}{2}$.
