a) \(x^3-2x^2y-4x+8y\\ =x^2\left(x-2y\right)-4\left(x-2y\right)\\ =\left(x^2-4\right)\left(x-2y\right)\\ =\left(x-2\right)\left(x+2\right)\left(x-2y\right)\)
b) \(2a^3+16b^3\\ =2\left(a^3+8b^3\right)\\ =2\left(a+2b\right)\left(a^2-2ab+4b^2\right)\)
c) \(x^2+5x+6\\ =x^2+2x+3x+6\\ =x\left(x+2\right)+3\left(x+2\right)\\ =\left(x+2\right)\left(x+3\right)\)
a) \(x^3-2x^2y-4x+8y\)
\(=x^2\left(x-2y\right)-4\left(x-2y\right)\)
\(=\left(x-2y\right)\left(x^2-4\right)\)
\(=\left(x-2y\right)\left(x-2\right)\left(x+2\right)\)
b) \(2a^3+16b^3\)
\(=2\left(a^3+8b^3\right)\)
\(=2\left(a+2b\right)\left(a^2-2ab+4b^2\right)\)
c) \(x^2+5x+6\)
\(=x^2+2x+3x+6\)
\(=x\left(x+2\right)+3\left(x+2\right)\)
\(=\left(x+2\right)\left(x+3\right)\)
câu b rút 2 ra rồi còn
a\(^{\text{3}}\)+ (2b)\(^{\text{3}}\) rồi áp dụng HĐT
a) x3-2x2y-4x+8y
=(x3-2y)-(4x-8y)
=x2(x-2y)-4(x-2y)
=(x-2y)(x2-4)
c) x2+5x+6
=x2+2x+3x+6
=(x2+2x)+(3x+6)
=x(x+2)+3(x+2)
=(x+2)(x+3)
