Đáp án:
Giải thích các bước giải:
\(\begin{array}{l}1)x\left( {x + y} \right) - 5x - 5y = x\left( {x + y} \right) - 5\left( {x + y} \right) = \left( {x + y} \right)\left( {x - 5} \right)\\2)3{x^3}y - 3x{y^3} + {x^2} - {y^2} = 3xy\left( {{x^2} - {y^2}} \right) + \left( {{x^2} - {y^2}} \right) = \left( {{x^2} - {y^2}} \right)\left( {3xy + 1} \right)\\3)\,{x^2} - 2xy + {y^2} - {2^2} = {\left( {x - y} \right)^2} - {2^2} = \left( {x - y + 2} \right)\left( {x - y - 2} \right)\\4)\,{\left( {2x + 3} \right)^2} - \left( {{x^2} - 6x + 9} \right) = {\left( {2x + 3} \right)^2} - {\left( {x - 3} \right)^2}\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \left( {2x + 3 + x - 3} \right)\left( {2x + 3 - x + 3} \right)\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \,3x\left( {x + 6} \right)\\5)\,{x^2} - xy + 5x - 5y = x\left( {x - y} \right) + 5\left( {x - y} \right) = \left( {x - y} \right)\left( {x + 5} \right)\\6)\,{x^2} - {y^2} + 5x - 5y = \left( {x - y} \right)\left( {x + y} \right) + 5\left( {x - y} \right) = \left( {x - y} \right)\left( {x + y + 5} \right)\\8)\,xy\left( {x - y} \right) + yz\left( {y - z} \right) + zx\left( {z - x} \right) = {x^2} - {y^2} + {y^2} - {z^2} + {z^2} - {x^2} = 0\\9)\,{x^2} + 6x + 9 - 25{z^2} = {\left( {x + 3} \right)^2} - {\left( {5z} \right)^2} = \left( {x + 3 - 5z} \right)\left( {x + 3 + 5z} \right)\end{array}\)
Các câu còn lại bạn làm tiếp nhé
