Question

BT16: Cho\(A=5xy^2-4x^2y-6xy^2,B=8yx^2-4y^2x+3y^2\)và\(C=-2xy^2+3yx^2+5x^2\)

a, Tính A-B+C

b, Tính 2(A+B)+C

Answer 1

\(a,A-B+C\)

\(=\left(5xy^2-4x^2y-6xy^2\right)-\left(8yx^2-4y^2x+3y^2\right)+\left(-2xy^2+3yx^2+5x^2\right)\)

\(=5xy^2-4x^2y-6xy^2-8yx^2+4y^2x-3y^2-2xy^2+3yx^2+5x^2\)

\(=\left(5xy^2-6xy^2-2xy^2+4xy^2\right)+\left(-4x^2y-8x^2y+3x^2y\right)+\left(-3y^2+5x^2\right)\)

\(=xy^2-9x^2y-3y^2+5x^2\)

\(b,2\left(A+B\right)+C=2A+2B+C\)

\(=2\left(5xy^2-4x^2y-6xy^2\right)+2\left(8yx^2-4y^2x+3y^2\right)-2xy^2+3yx^2+5x^2\)

\(=10xy^2-8x^2y-12xy^2+16x^2y-8xy^2+6y^2-2xy^2+3x^2y+5x^2\)

\(=-12xy^2+11x^2y+5x^2+6y^2\)