\(a)\) \(x^2-2x-4y^2-4y\)
\(=\)\(\left(x^2-2x+1\right)-\left(4y^2+4y+1\right)\)
\(=\)\(\left(x-1\right)^2-\left(2y+1\right)^2\)
\(=\)\(\left(x-1-2y-1\right)\left(x-1+2y+1\right)\)
\(=\)\(\left(x-2y-2\right)\left(x+2y\right)\)
\(=\)\(2\left(x-y\right)\left(x+2y\right)\)
Chúc bạn học tốt ~
a) Ta có x2 - 2x - 4y2 - 4y
= x2 - 2x + 1 - 4y2 - 4y - 1
= (x - 1)2 - (4y2 + 4y + 1)
= (x - 1)2 - (2y + 1)2
= (x - 1 - 2y - 1)(x - 1 + 2y + 1)
= (x - 2y - 1)(x + 2y)
sory nhé a) kq cuối là :
\(\left(x-2y-2\right)\left(x+2y\right)\)
\(d)\) \(3x^2-3y^2-2\left(x-y\right)^2\)
\(=\)\(\left(3x^2-3y^2\right)-2\left(x-y\right)^2\)
\(=\)\(3\left(x^2-y^2\right)-2\left(x-y\right)^2\)
\(=\)\(3\left(x-y\right)\left(x+y\right)-2\left(x-y\right)\left(x-y\right)\)
\(=\)\(\left(x-y\right)\left(3x-3y\right)-\left(x-y\right)\left(2x-2y\right)\)
\(=\)\(\left(x-y\right)\left(3x-3y-2x+2y\right)\)
\(=\)\(\left(x-y\right)\left(x-y\right)\)
\(=\)\(\left(x-y\right)^2\)
\(e)\) \(x^3-4x^2-9x+36\)
\(=\)\(\left(x^3-9x\right)-\left(4x^2-36\right)\)
\(=\)\(x\left(x^2-9\right)-4\left(x^2-9\right)\)
\(=\)\(\left(x^2-9\right)\left(x-4\right)\)
\(=\)\(\left(x-3\right)\left(x+3\right)\left(x-4\right)\)
\(f)\) \(x^2-y^2-2x-2y\)
\(=\)\(\left(x^2-y^2\right)-\left(2x+2y\right)\)
\(=\)\(\left(x-y\right)\left(x+y\right)-2\left(x+y\right)\)
\(=\)\(\left(x+y\right)\left(x-y-2\right)\)
Chúc bạn học tốt ~