The Circuit Shown Below, Let Use Superposition Principle to Find $V _ { 1 }$

Essay

the circuit shown below, let $$\mathrm { I } _ { \mathrm { s } } = 3 \mathrm {~mA} , \mathrm {~V} _ { \mathrm { s } } = 6 \mathrm {~V} , \mathrm { R } _ { 1 } = 1 \mathrm { k } \Omega , \mathrm { R } _ { 2 } = 1.2 \mathrm { k } \Omega , \mathrm { R } _ { 3 } = 1.2 \mathrm { k } \Omega , \mathrm { R } _ { 4 } = 4 \mathrm { k } \Omega$$
Use superposition principle to find $V _ { 1 }$ .