Đáp án:
16) \(\left( {2x - 5} \right)\left( {3x + 4} \right)\)
Giải thích các bước giải:
\(\begin{array}{l}
10)8{x^2} + 30x + 7 = 8{x^2} + 2x + 28x + 7\\
= 2x\left( {4x + 1} \right) + 7\left( {4x + 1} \right)\\
= \left( {4x + 1} \right)\left( {2x + 7} \right)\\
11)4{x^3} - 12{x^2} + 9x = x\left( {4{x^2} - 12x + 9} \right)\\
= x\left( {4{x^2} - 6x - 6x + 9} \right)\\
= x\left[ {2x\left( {2x - 3} \right) - 3\left( {2x - 3} \right)} \right]\\
= x{\left( {2x - 3} \right)^2}\\
12){\left( {2x + 1} \right)^2} - {\left( {x - 3} \right)^2}\\
= \left( {2x + 1 - x + 3} \right)\left( {2x + 1 + x - 3} \right)\\
= \left( {x + 4} \right)\left( {3x - 2} \right)\\
13)5\left( {x - y} \right) - {\left( {x - y} \right)^2}\\
= \left( {x - y} \right)\left( {5 - x + y} \right)\\
14)ab + {c^2} - ac - bc\\
= a\left( {b - c} \right) + c\left( {c - b} \right)\\
= \left( {b - c} \right)\left( {a - c} \right)\\
15)4{x^2} - 4x + 1 - {y^2}\\
= {\left( {2x - 1} \right)^2} - {y^2}\\
= \left( {2x - 1 - y} \right)\left( {2x - 1 + y} \right)\\
16)6{x^2} - 15x + 8x - 20\\
= 3x\left( {2x - 5} \right) + 4\left( {2x - 5} \right)\\
= \left( {2x - 5} \right)\left( {3x + 4} \right)
\end{array}\)
