Question

what should be added to a²+b²+b² to obtain 4a²-2ab?

Answer 1

let added no be x
then
${a}^{2} + 2 {b}^{2} + x = 4 {a}^{2} - 2ab \\ x = 4 {a}^{2} - 2ab - {a}^{2} - 2{b}^{2} \\ x = 3 {a}^{2} - 2ab - 2 {b}^{2}$

Answer 2

Solution.....

2b^2-3a^2+2ab