Question
Multiply polynomial $ \, \color{blue}{ 4x^3+3x } \, $ by $ \, \color{orangered}{ 2x+5 }$.
Answer
$$ \left( \color{blue}{4x^3+3x} \right) \cdot \left( \color{orangered}{2x+5} \right) = 8x^4+20x^3+6x^2+15x $$
Explanation
In this example we are multiplying two binomials so FOIL method can be used.
$$ \begin{aligned} \left( \color{blue}{ 4x^3+3x}\right) \cdot \left( \color{orangered}{ 2x+5}\right) &= \underbrace{ \color{blue}{4x^3} \cdot \color{orangered}{2x} }_{\text{FIRST}} + \underbrace{ \color{blue}{4x^3} \cdot \color{orangered}{5} }_{\text{OUTER}} + \underbrace{ \color{blue}{3x} \cdot \color{orangered}{2x} }_{\text{INNER}} + \underbrace{ \color{blue}{3x} \cdot \color{orangered}{5} }_{\text{LAST}} = \\ &= 8x^4 + 20x^3 + 6x^2 + 15x = \\ &= 8x^4 + 20x^3 + 6x^2 + 15x = \\ &= 8x^4+20x^3+6x^2+15x; \end{aligned} $$This page was created using
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