Question

Bài 1 tính nhanh

a/ 156^2-112.156+56^2

b/ x^2-2xy-4z^2+y^2

Bài 2

a/ x^2-y^2-5x+5y

b/ x^2-4x-12

c/ 3x^2-6xy-48+3y^2

Answer 1

Bài 1:

\(a,=\left(156-56\right)^2=100^2=10000\\ b,=\left(x-y\right)^2-4z^2=\left(x-y-2z\right)\left(x-y+2z\right)\)

Bài 2:

\(a,=\left(x-y\right)\left(x+y\right)-5\left(x-y\right)=\left(x-y\right)\left(x+y-5\right)\\ b,=x^2+2x-6x-12=\left(x+2\right)\left(x-6\right)\\ c,=3\left(x^2-2xy-16+y^2\right)=3\left[\left(x-y\right)^2-16\right]\\ =3\left(x-y-4\right)\left(x-y+4\right)\)