Ta có : 5x2 + 14x - 3
= 5x2 + 15x - x - 3
= (5x2 + 15x) - (x + 3)
= 5x(x + 3) - (x + 3)
= (x + 3)(5x - 1)
Phân tích đa thức thành nhân tử 5x2+14x−3
Theo đề bài ta có:
\(5x^2+14x-3\)
\(\Leftrightarrow5x^2+15x-x-3\)
\(\Leftrightarrow\left(5x^2+15x\right)-\left(x-3\right)\)
\(\Leftrightarrow5x\left(x-3\right)-\left(x+3\right)\)
\(\Leftrightarrow\left(3x\right)\left(5x-1\right)\)
\(5x^2+14x-3\)
\(\Leftrightarrow5x^2+15x-x-3\)
\(\Leftrightarrow\left(5x^2+15x\right)-\left(x-3\right)\)
\(\Leftrightarrow5x\left(x-3\right)-\left(x+3\right)\)
\(\Leftrightarrow3x\left(5x-1\right)\)
5x^2+14x-3
=5x^2+15x-x-3
=5x(x+3)-(x+3)
=(x+3)(5x-1)
