Question

A= x²-2x-y²+3y-1

B= -2x²+3y²-5x+y+3

Tính A+B

Tính A-B

Answer 1

a) A+B

A+B=\(\left(x^2-2x-y^2+3y-1\right)\)+\(\left(-2x^2+3y^2-5x+y+3\right)\)

       =\(x^2-2x-y^2+3y-1+\left(-2x^2\right)+3y^2-5x+y+3\)

       =\(\left(x^2-2x^2\right)+\left(-2x-5x\right)+\left(y^2+3y^2\right)+\left(3y+y\right)+\left(-1+3\right)\)

       =\(-x^2-7x+4y^2+4y+2\)

       =\(x^2+4y^2-7x+4y+2\)

b) A-B

A-B=\(\left(x^2-2x-y^2+3y-1\right)-\left(-2x^2+3y^2-5x+y+3\right)\)

      =\(x^2-2x-y^2+3y-1+2x^2-3y^2+5x-y-3\)  

      =\(\left(x^2+2x^2\right)+\left(-2x+5x\right)+\left(-y^2-3y^2\right)+\left(3y-y\right)+\left(1-3\right)\)

      =\(3x^2+3x-4y^2+2y-2\)

      =\(3x^2-4y^2+3x+2y-2\)

 mk nha Tân Thái Công Chúa