Queen Material Giải:
\(25\left(x+y\right)^2-16\left(x-y\right)^2\)
\(=25\left(x^2+2xy+y^2\right)-16\left(x^2-2xy+y^2\right)\)
\(=25x^2+50xy+25y^2-16x^2+32xy-16y^2\)
\(=9x^2+82xy+9y^2\)
\(=x\left(9x+y\right)+9y\left(9x+y\right)\)
\(=\left(x+9y\right)\left(9x+y\right)\).