Question

multiply the polynomials.
\begin{align}&12a^{2}+2a - 5\\times&5a - 4\hlineend{align}

Explanation:

Step1: Distribute $5a$

$5a(12a^{2}+2a - 5)=60a^{3}+10a^{2}-25a$

Step2: Distribute $- 4$

$-4(12a^{2}+2a - 5)=-48a^{2}-8a + 20$

Step3: Combine like - terms

$(60a^{3}+10a^{2}-25a)+(-48a^{2}-8a + 20)=60a^{3}+(10a^{2}-48a^{2})+(-25a - 8a)+20=60a^{3}-38a^{2}-33a + 20$

Answer:

$60a^{3}-38a^{2}-33a + 20$