Phân tích đ thức thành nhân tử.
1) 2x2 + 3x - 27 =
= 2x2 + 9x - 7x - 27
= (2x2- 6x) + (9x + 27)
= 2x(x - 3) + 9(x - 3)
= (x - 3)(2x + 9)
2) 49x2 + 28x - 5 =
= (7x)2 + 2.7x.2 + 22 - 22 - 5
= (7x + 2)2 - 9
= (7x + 2)2 - 32
= (7x + 2 + 3)(7x + 2 - 3)
= (7x + 5)(7x - 1)
3) 2x2 - 5xy - 3y2=
= 2x2 - 6xy + xy - 3y2
= (2x2 - 6xy) + (xy - 3y2)
= 2x(x - 3y) + y(x - 3y)
= (x - 3y)(2x + y)
1) \(2x^2\)\(+3x-27\)
\(=2x^2+6x-9x-27\)
\(=2x\left(x+3\right)-9\left(x+3\right)\)
\(=\left(2x-9\right)\left(x+3\right)\)
2) Nghiệm lẻ
3)\(2x^2-5xy-3y^2\) \(\)
\(=2x^2-6xy+xy-3y^2\)
\(=2x\left(x-3y\right)+y\left(x-3y\right)\)
\(=\left(x-3y\right)\left(2x+y\right)\)
