mk nhầm A=(2a^3.b^2.x^4.y)^3.(-3/10.b^5.x^2.z^3) phai là A=(2a^3.b^2.x^4.y)^3.(-3/10.b^5.x^2.y^2.z^3)
A=(2a^3.b^2.x^4.y)^3.(-3/10.b^5.x^2 .y^2.z^3)
=(2^3.a^9.b^6.x^12.y^3).(-3/10.b^5.x^2.y^2.z^3)
=8.a^9.b^11.x^14.y^5.z^3.(-3/10)
=-12/5..a^9.b^11.x^14.y^5.z^3
a)ta co 21=14+5+3
=) x,y,z, la bien
a ,b la hằng
b)ta co 31 =14+9+5+3
=)biến la a, x,y,z
hang la b
c)ta co 8=3+5
bien la y,z
hang la a,b,x