If a,b,c are real and a^2 + b^2 + c^2= 2(a-b-c)-3 the value of 2a -3b+4c is what?

[Dhanalakshmi]

If a,b,c are real and a² + b² + c²= 2(a-b-c)-3 the value of 2a -3b+4c is what??

[Dhanalakshmi]