Question

tính (rút gọn) :

a) -5xy(3x²y – 5xy +y²)

b) (x + 8)² -2(x + 8) (x – 2) + (x – 2)²

Answer 1

a) -5xy(3x²y – 5xy +y²)

=-15x³y²+25x²y²-5xy³

 

b) (x + 8)² -2(x + 8) (x – 2) + (x – 2)²

=[(x+8)-(x-2)]²

=(x+8-x+2)²

=10²

=100

 

Answer 2

\(a,-5xy\left(3x^2y-5xy+y^2\right)=-15x^3y^2+25x^2y^2-5xy^3\)

\(b,\left(x+8\right)^2-2\left(x+8\right)\left(x-2\right)+\left(x-2\right)^2=\left[x+8-\left(x-2\right)\right]^2=\left[x+8-x+2\right]^2=10^2=100\)