Question

a.A-(xy+x²-y²)=x²+y² b.(15x²-2xy)+A=6x²+9xy-y² c.(x²-y²+3y²-1)-A=x²-2y²

Answer 1

a) \(A-\left(xy+x^2-y^2\right)=x^2+y^2\)

\(\Rightarrow A=x^2+y^2+xy+x^2-y^2\)

\(\Rightarrow A=2x^2+xy\)

b) \(\left(15x^2-2xy\right)+A=6x^2+9xy-y^2\)

\(\Rightarrow A=6x^2+9xy-y^2-15x^2+2xy\)

\(\Rightarrow A=11xy-9x^2-y^2\)

c) \(\left(x^2-y^2+3y^2-1\right)-A=x^2-2y^2\)

\(\Rightarrow A=x^2-y^2+3y^2-1-x^2+2y^2\)

\(\Rightarrow A=4y^2-1\)