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多項式因式分解計算器
逐步因式分解多項式
此計算器會嘗試對任何多項式（如二項式、三項式、二次式等）進行因式分解，並顯示步驟。使用的方法包括：公因式分解（提取單項式公因式）、二次式因式分解、分組分解與重分組、和/差的平方、和/差的立方、平方差、立方和/差，以及有理根定理。此計算器可接受一元與多元多項式。
Solution
Your input: factor $$$3 r^{2} + 8 r + 5$$$.
To factor the quadratic function $$$3 r^{2} + 8 r + 5$$$, we should solve the corresponding quadratic equation $$$3 r^{2} + 8 r + 5=0$$$.
Indeed, if $$$r_1$$$ and $$$r_2$$$ are the roots of the quadratic equation $$$ar^2+br+c=0$$$, then $$$ar^2+br+c=a(r-r_1)(r-r_2)$$$.
Solve the quadratic equation $$$3 r^{2} + 8 r + 5=0$$$.
The roots are $$$r_{1} = -1$$$, $$$r_{2} = - \frac{5}{3}$$$ (use the quadratic equation calculator to see the steps).
Therefore, $$$3 r^{2} + 8 r + 5 = 3 \left(r + 1\right) \left(r + \frac{5}{3}\right)$$$.
$${\color{red}{\left(3 r^{2} + 8 r + 5\right)}} = {\color{red}{\left(3 \left(r + 1\right) \left(r + \frac{5}{3}\right)\right)}}$$
Simplify: $$$3 \left(r + 1\right) \left(r + \frac{5}{3}\right)=\left(r + 1\right) \left(3 r + 5\right)$$$.
Thus, $$$3 r^{2} + 8 r + 5=\left(r + 1\right) \left(3 r + 5\right)$$$.
Answer: $$$3 r^{2} + 8 r + 5=\left(r + 1\right) \left(3 r + 5\right)$$$.