\(a,x^2-9+\left(x-3\right)^2\)

\(=x^2-9+x^2-6x+9\)

\(=2x^2-6x\)

\(b,x^34x^2+4x-xy^2\)

\(=x\left(x^2-4x+4-y^2\right)\)

\(=x\left[\left(x-2\right)^2-y^2\right]\)

\(=x\left(x-2-y\right)\left(x-2+y\right)\)

\(c,3x^2-7x-10\)

\(=3x^2+3x-10-10\)

\(=3x\left(x+1\right)-10\left(x+1\right)\)

\(=\left(3x-10\right)\left(x+1\right)\)

\(126y^3+\left(x-5y\right)x^2+25y^2+5xy\)

\(=120y^3+xx^2-5x^2y+25y^2+5xy\)

\(=120y^3+x^3-5x^2y+25y^2+5xy\)

Chúc bạn học tốt!

1,My suicase is large(large) than your suicase.

2, This scarf is more beautiful(beautiful) than the one in the window.

3. The palace hotel was more expensive( expensive) than the grosvenor.

4, John is a better(good) gardener than stuart.

5, They are not going to the worst(bad) hotel.

chọn C.at/of