b. trị tuyệt đối 3x - 2 +x = 11

3x−2+x=11⇔3x−2=11−x

⇔DK:11−x≥0⇔x≤11PT⇔3x−2=11−x3x−2=−11−x⇔4x=132x=−9             ⇔x=134x=−92(tm)

S=−92;134