Question

Answer 1

Bài 7:

a. $A=-6x^5+6x^3-x^2$

b. $B=-3x^8-6x^7+2x^4$

c. $C=4x^4(x^2-\frac{1}{2}x+\frac{1}{4})$

$=4x^6-2x^5+x^4$
 

Answer 2

Bài 8:

a. $M=-6x^6y^4+3x^4y^3+x^8y$

b. $N=2x^3y^2-6xy^4+\frac{2}{3}x^5y^4$

c. \(P=(-x^2y^3+\frac{1}{4}y^4-\frac{2}{9}xy).36x^2y^2\)

\(=-36x^4y^5+9x^2y^6-8x^3y^3\)

Answer 3

Bài 9:

a. 

\(A=4x^2(-3x^2+1)+6x^2(2x^2-1)+x^2\)

\(=-12x^4+4x^2+12x^4-6x^2+x^2=-x^2\)

b.

\(B=-2x^2y^3-2x^2y^2+x^2-2x^2y^3-2x^2y^2\)

\(=-4x^2y^3-4x^2y^2+x^2\)

c.

\(C=4x^2y^2(1+2y)+8x^2(1-y^3)-x^2(4y^2+1)\)

\(=4x^2y^2+8x^2y^3+8x^2-8x^2y^3-4x^2y^2-x^2\)

\(=7x^2\)