!x-1!+!2x-6!=12
!x-1!+2.!x-3!=12
lập bảng xét dấu cho đỡ nhầm
x | -vc | 1 | 3 | +vc | |
!x-1! | -x+1 | 0 | x-1 | 4 | (x-1) |
2!x-3! | -2(2x-3) | -8 | -2(x-3 | 0 | 2(x-3) |
!x-1!+2!x-3! | -x+1-2(x-3) | -8 | (x+1)-2(x-3) | 4 | (x+1)+2(x-3) |
*khi x<-1
!x-1!+2!x-3!=-x+1-2(x-3)=-x+1-2x+6=-3x+7=12=> -3x=5=>x=5/(-3)=-5/3 (nhan)
*khi \(1\le x<3\)
!x-1!+2!x-3!=(x-1)-2(x-3)=x-1-2x+6=-x+5=12=> x=-7 (loai)
*khi \(x\ge3\)
!x-1!+2!x-3!=(x-1)+2(x-3)=x-1+2x-6=3x-7=12=> x=19/3(nhan)