y³+(a+17)y²+(38-a)y-56=0y³-y²+(a+18)y²-(a+18)y+56y-56=0y²(y-1)+(a+18)y(y-1)+56(y-1)=0(y-1)[y²+(a+18)y+56]=0y=1是方程的根,且為整數(shù),只要判斷y²+(a+18)y+56=0的兩根....x²-|2x-1|-4=0

x≥1/2時(shí)，方程變?yōu)閤²-2x-3=0
(x-3)(x+1)=0
x=3或x=-1(舍去)
x<1/2時(shí)，方程變?yōu)閤²+2x=5
(x+1)²=6
x=-1+√6(舍去)或x=-1-√6
綜上，得x=3或x=-1-√6
3+(-1-√6)=2-√6