Question

[super xity]

phân tích thành đa thức nhân tử

9( x + 5)^2 - ( x -7 )^2

25( x - y)^2 - 16 ( x + y)^2

Answer 1

[Teen]

\(9\left(x+5\right)^2-\left(x-7\right)^2\)

\(=\left(3x+15\right)^2-\left(x-7\right)^2\)

\(=\left(3x+15-x+7\right)\left(3x+15+x-7\right)\)

\(=\left(2x+22\right)\left(4x+8\right)\)

\(=2\left(x+11\right).4\left(x+2\right)\)

\(=8\left(x+11\right)\left(x+2\right)\)