a) \(3x-15y\)
\(=3.x-3.5y=3-\left(x-5y\right)\)
Câu 13:
a)\(3x-15y=3\left(x-5y\right)\)
b)\(x^3+2x^2+x=x\left(x^2+2x+1\right)=x\left(x+1\right)^2\)
c)\(16+2xy-x^2-y^2=16-\left(x^2-2xy+y^2\right)=4^2-\left(x-y\right)^2=\left[4-\left(x-y\right)\right]\left[4+\left(x-y\right)\right]=\left(4-x+y\right)\left(4+x-y\right)\)