a) 1/3x^2y^5 × (-3x^3y) + x^5y^6
<=> (1/3 × -3/5 × x^2 × x^3 × y^5 × y) + x^5y^6
<=> -1/5x^5y^6 + x^5 y^6
<=> -1/5 x^5y^6
b) 5x^2 × (-3/10x^2y) + 3/4x^3y^3
<=> (5×-3/10 × x × x^2 × y^2 × y) + 3/4x^3y^3
<=> -3/2 x^3y^3 + 3/4x^3y^3
<=> -3/4x^3y^3
c) 1/4x^4y (-2/3x^3y^2) - 1/3x^7y^3
<=> (1/4 × -2/3 × x^4 × x^3 × y × y^2) -1/3x^7y^3
<=> 1/6 x^7y^3 - 1/3x^7y^3
<=>-1/2x^7y^3
d)1/2xy^2 × (-2/3x^2y)^2 - 5xy(-1/2x^4y^3) + (-1/2x^2y)^2 × xy
<=> (1/2 × -4/9 × x × x^4 × y^2 × y^2) (- 5 × -1/2 × x × x^4 × y × y^3) + (1/4 × x^4 × x × y^2 × y^2)
<=> -2/9x^5y^4 - 5/2x^5x^4 + 1/4x^5y^4
<=> -89/36x^5y^4
e) 2/5x^4y^5 (5/4x^2 y^3) + 5/3x^2y^3 (-9/10x^4y^5)
<=> (2/5 × 5/4 × x^4 × x^2 × y^5 × y^3) + (5/3 × -9/10 × x^2 × x^4 × y^3 × y^5)
<=> 1/2x^6y^8 - 3/2x^6y^8
<=> -1x^6y^8
f) 1/2xy^2 × (-2/3x^2y)^2 - 5xy(-1/2x^4y^3) + (-1/2x^2y)^2 × xy^2
<=> (1/2 × -4/9 × x × x^4 × y^2 × y^2) (- 5 × -1/2 × x × x^4 × y × y^3) (-1/4x^4 × x × y^2 × y^2)
<=> 1/18x^5y^4 + 5/2x^5yx^5y^4 - 1/4x^5y^4
<=> 83/36x^5y^4
g) -5/2(xy)^2 × x^3 + 3/7(2x)^3(7/2xy)^2 - 1/3x × 3x^4y^2
<=> (-5/2 × x^2 × x^3 × y^2) + (3/7 × 2 ×7/2 × x^3 × x^2 × y^2)( -1/3 × 3 × x × x^4 × y^2)
<=> -5/2 × x^5 × y^2 + 3 × x^5 × y^2 - 1x^5y^2
<=> -15x^5y^2
Bạn kiểm tra lại có đúng không nha, có sai thì bỏ qua giúp!