[tex] ( \ frac{1}{4} x {} ^ {4} - \ frac{7}{6}x {} ^ {3} + 31x {} ^ {2} + 12 + x) + ( \ frac{1}{6} - \ frac{2}{3} x {} ^ {2} + 2x {} ^ {3} + 3x) - ( - \ frac{2}{3}x + \ frac{2}{3} + x {} ^ {2}) = [ / ?
[tex] ( \ frac{1}{4} x {} ^ {4} - \ frac{7}{6}x {} ^ {3} + 31x {} ^ {2} + 12 + x) + ( \ frac{1}{6} - \ frac{2}{3} x {} ^ {2} + 2x {} ^ {3} + 3x) - ( - \ frac{2}{3}x + \ frac{2}{3} + x {} ^ {2}) = [ / tex] .