a,|x-3|=12
=>x thuộc {15;-9}
b,|x-9|=39
=>x thuộc {48;-30}
a) /x-3 / - 16 =-4
x-3 - 16=-4 hoặc x-3-16=4
x-13=-4+16 hoặc x-3 =4+16
x-13=12 hoac x-3 =20
x=12+13 hoac x =20+3
x=26 hoac x=23
b)26-/x+9/=-13
26-x+9=-13 hoac26-x+9=13
x+9=26--13hoac x+9=26-13
x+9=39hoac x+9=13
x=39-9hoacx=13-9
x=30hoac x=4