a) 20x – 5y e) 4x y – 8xy + 10x y
c) x(x + y) – 6x – 6y h) 8x + 12x y – 16x y
d) 6x – 9x k) 4xy + 8xyz
Bài toán 2 : Phân tích đa thức sau thành nhân tử.
a) 3x(x +1) – 5y(x + 1) h) 3x (2y – 3z) – 15x(2y – 3z)
b) 3x(x – 6) – 2(x – 6) k) 3x(z + 2) + 5(-x – 2)
c) 4y(x – 1) – (1 – x) l) 18x (3 + x) + 3(x + 3)
d) (x – 3) + 3 – x m) 14x y – 21xy + 28x y
e) 7x(x – y) – (y – x) n) 10x(x – y) – 8y(y – x)
Đáp án:
$\begin{array}{l}
a)20x – 5y = 5\left( {4x – y} \right)\\
c)x\left( {x + y} \right) – 6x – 6y = x\left( {x + y} \right) – 6\left( {x + y} \right) = \left( {x + y} \right)\left( {x – 6} \right)\\
e)4xy – 8xy + 10xy = 6xy\\
b2)\\
a)3x\left( {x + 1} \right) – 5y\left( {x + 1} \right) = \left( {x + 1} \right)\left( {3x – 5y} \right)\\
b)\,3x\left( {x – 6} \right) – 2\left( {x – 6} \right) = \left( {x – 6} \right)\left( {3x – 2} \right)
\end{array}$
Các câu còn lại em làm tương tự nhé